depends where you are getting your foreign exchange values from.
if you need uptodate values you can find providers on the web, otherwise you need a local table.
Personally I'd use a local table, insert all the various currencies you support with a forex value. in this case, say, thats gong to be CDN, 1.01926, SFR 0.89590, GBP 0.63570...
but also define your base currency in this case USD with a conversion factor of 1. that way round you treat all calculations the same.
bear in mind that currency conversions are a potential minefield. you need to have a thorough understanding of how the information is consumed. its often a requirement to store the exchange rate + the date and time of that rate as part of the transaction.
also some consumers of information demand a specific level of precision. ferinstance in financial reporting you need to treat all times consistently. the sum should reflect the sum of the individual items converted as the prevailing rate. and that calcualtion must be consistent across the system. so if you only refer to the sub total in other reports / forms etc you must make certain the sub total is the sum of the items coverted, not the sum converted
I'd rather be riding on the Tiger 800 or the Norton