Hiding product layout when gift voucher selected

Question

In the example below I am using the "retail price" in my product layouts, but I don't want to show that line when a product is a gift voucher. Don't be confused that I use retail price and case price interchangeably.
I gave the line an id of "caseprice" and now I want to hide it whenever gift voucher is selected in the product details.
I've included below what i've been working on....Can anyone see what i'm doing wrong here?  THANKS!
<div class="shop-product-small">
<h4>{tag_name}</h4>
<div class="image">{tag_smallimage}</div>
<ul>
    <li class="price">Price: <strong>{tag_saleprice}</strong> </li>
    <li class="retail" id="caseprice">Case price: {tag_retailprice} per bottle</li>
    <li class="custom2">{tag_custom2}</li>
    <li class="custom1">{tag_custom1}</li>
    <li class="quantity">Qty: <strong>{tag_addtocartinputfield}</strong> {tag_addtocart}</li>
</ul>
</div>
<script language="javascript"><!-- 
var caseprice = "{tag_giftvoucher}"; 
if caseprice == "1") { 
     document.getElementById("caseprice").style.display = 'none';
//--></script>

Answer 1

Hi Oli,
We need this too - did you have any luck?
We are so confused as on our website we have no section to buy a gift voucher yet 2 customers have and have redeemed them?!?
Cheers,
DD