Canadian BC users, how are you dealing with HST, GST and PST/QST?

Question

Hi, I'm new here and I've been building my first BC eCommerce site for a client for almost a year. It's a business to business site, dealing with about 5000 SKUs. It's currently in trial mode, and we're about to go live with it. I have a problem with taxes I hoped I'd be able to sort out, but haven't found a solution.
My client's head office is in Ontario and they sell from there, and also from Quebec, though online sales will be limited from Ontario for now. Ontario, like B.C., where I am, and a number of other provinces have HST. The remaining provinces have GST and PST/QST, except Alberta, which only has GST. My client sells thoughout Canada, and also to the U.S.
Scenario 1) When one sells from an HST province to a customer in another HST province, the seller must collect and remit the HST for the buyer's province. For example, I work from B.C. with 12% HST, and my client has 13% HST in Ontario. I have to invoice them for my services, collecting and remitting 13% HST.
Scenario 2) When one sells from any province to a customer in a non-HST province other than Quebec, the seller charges GST and is encouraged, and depending on the province they are selling to, required, to register for that province's PST and collect and remit that tax as well. Otherwise the customer is required to self-assess the PST on the purchase.
Scenario 3) When one sells from any province to a customer in Quebec, they must apply the GST to the purchase, and then apply the QST (Quebec Sales Tax) to that total. Again, out of province sellers are expected to collect and remit the QST.
Scenario 1 is fine. Currently I've set up all HST provinces with their corresponding rate.
Scenario 2 is problematic from a legal taxation standpoint. I've set up all GST+PST provinces and Quebec with 5% GST only. This will not be acceptable to my client as their sales volumes are quite high and they have to remit other province's PST.
Scenario 3 seems impossible on BC, but will become a lesser problem until January 2013, when Quebec changes to Scenario 2 (i.e. the QST will no longer piggy-back the GST but will be raised so there is no change to the total tax)
Further, most businesses will want to see the GST and PST appear separately on the invoice, not calculated together as seems to be the case now.
Has anyone managed to set up GST and PST/QST in the system, so both taxes appear in the cart/checkout process, and separately on the invoice?
Thanks for any assistance!

Answer 1

This might require the discussion to move to the advanced code development section, but I'll post it here first anyway.
So after about 2 weeks, I'm not sure there's a solution to this. I've tried a variety of JavaScript and JQuery approaches to do a show/hide of the appropriate tag based on the province chosen in the {tag_shippingoptions} drop down. The cleanest way was with JQuery and I got it to work outside of Business Catalyst, but not when implemented in my cart.
The problems seems to be threefold.
1. The onchange of the "shipping state" dropdown calls ApplyTaxRate() in an unmodifiable back-end .js file. If I try to have local JS or JQ work on the same function call to do my show/hide, not only does the show/hide not work, but it breaks communication with the back-end .js so no taxes get calculated/updated.
2. If I create my own shipping menus calling the same functions (acutally just copy/pasted the inspected HTML), the taxes update OK, but the menu selections don't persist, AND if I then inject my show/hide, the show/hide doesn't work and all the functionality of the ApplyTaxRate function breaks.
3. If I try to call an additional function for the show/hide, from the onchange of my own menu, the ApplyTaxRate function works, but the additional fucntion doesn't work as it does outside of BC.
Here is my partial code. Any help?
<div class="shippingStateDiv"><span id="shippingStateSpan">Destination State<br />
            </span><select onchange="ApplyTaxRate(this.value,4638834,1,1,332304);taxDisplay(this.value);" class="shippingDropDown" id="shippingState" name="shippingState">
            <option value="-1">Please Select</option>
            <option value="147264">AB</option>
            <option value="130632">BC</option>
            <option value="147266">MB</option>
            <option value="130633">NB</option>
            <option value="130634">NL</option>
            <option value="130635">NS</option>
            <option value="147269">NT</option>
            <option value="147270">NU</option>
            <option value="130631">ON</option>
            <option value="147268">PE</option>
            <option value="147267">QC</option>
            <option value="147265">SK</option>
            <option value="147271">YT</option>
            </select></div>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js"></script>
        <script>
function taxDisplay(id) {
    var mySel = $("#shippingOptions").children("option:selected").text().replace(/\s/g,"")
    $('.answers').hide() 
    $('.answer'+mySel).show()       
</script>
<td><strong>
            <div class="answerPleaseSelect answers" style="display: none;">Choose Dest. State</div>
            <div class="answerAB answers" style="display: none;">GST: {tag_invoicetotaltaxamount}</div>
            <div class="answerBC answers" style="display: none;">HST: {tag_invoicetotaltaxamount}</div>
            <div class="answerMB answers" style="display: none;">{tag_invoicetotaltaxamount,MB,7,GST,PST}</div>
            <div class="answerNB answers" style="display: none;">HST: {tag_invoicetotaltaxamount}</div>
            <div class="answerNL answers" style="display: none;">HST: {tag_invoicetotaltaxamount}</div>
            <div class="answerNS answers" style="display: none;">HST: {tag_invoicetotaltaxamount}</div>
            <div class="answerNT answers" style="display: none;">GST: {tag_invoicetotaltaxamount}</div>
            <div class="answerNU answers" style="display: none;">GST: {tag_invoicetotaltaxamount}</div>
            <div class="answerON answers" style="display: none;">HST: {tag_invoicetotaltaxamount}</div>
            <div class="answerPE answers" style="display: none;">{tag_invoicetotaltaxamount,PE,10.5,GST,PST}</div>
            <div class="answerQC answers" style="display: none;">{tag_invoicetotaltaxamount,QC,9.975,GST,QST}</div>
            <div class="answerSK answers" style="display: none;">{tag_invoicetotaltaxamount,SK,5,GST,PST}</div>
            <div class="answerYT answers" style="display: none;">GST: {tag_invoicetotaltaxamount}</div>
            </strong></td>