Proper way to do rounding for currency conversion in Paypal?

Question

I'm building an ecommerce site integrated with paypal.

We take multiple currencies, so I want to make sure that (for accounting reasons) i'm correctly performing any math for currency conversion.

After multiplying the currency conversion * the original currency, I always end up with lots of trailing numbers after the decimal point.

Is there a standard way to do this? Should I truncate or round? Do I need to round multiple times in case rounding the 1/1000 decimal will affect rounding the 1/100 decimal?

Should I be doing something like:

Math.Round(Math.Round(x, 3), 2)

I've been having trouble finding good information about how this is done (hopefully US and Europe are the same).

Answer 1

if your site has multiple currencies then use this to correctly round decimals according to the current user's currency and culture :

int currencyDecs = System.Threading.Thread.CurrentThread.CurrentCulture.NumberFormat.CurrencyDecimalDigits;
decimal roundedDecimalPrice = Math.Round(decimalPrice, currencyDecs, MidpointRounding.AwayFromZero);