Math.round produces inconsistent results

Question

We've been developing a tax calculator using the Flash 4 SDK in Flash Builder 4, and have experienced difficulties with rounding numbers - for example, the following statement:
     Alert.show(Math.round((8.325 * 100.0)) + ":" + Math.round(832.5));
Both of the values rounded above should equal 833, however, the first one shows 832, while the second shows 833.  If both of the expressions inside the Math.round() functions equal 832.5, then how are the resulting values different?

Answer 1

Thanks, Shongrunden - I found that same link literally a minute or two before I saw your response - after some preliminary testing, it looks like the following functions work well as a workaround:
* Corrects errors caused by floating point math.
public function correctFloatingPointError(number:Number, precision:int = 5):Number
     //default returns (10000 * number) / 10000
     //should correct very small floating point errors
     var correction:Number = Math.pow(10, precision);
     return Math.round(correction * number) / correction;
* Tests if two numbers are almost equal.
public function fuzzyEquals(number1:Number, number2:Number, precision:int = 5):Boolean
     var difference:Number = number1 - number2;
     var range:Number = Math.pow(10, -precision);
     //default check:
     //0.00001 < difference > -0.00001
     return difference < range && difference > -range;