shouldn't matter. Anything up to a quarter canadian spends exactly like an american one. If you have a lot of toonies or loonies, (ie 2 dollar and 1 dollar coins) then you definitely will have to go to a currency exchange. As for canadian pennies, save them because they are 99% copper and now that canada is melting them down, I think you can also, or at least sell them for copper prices. Check your stash for pre 1964ish (forgot the dates exactly) because quarters and dimes can be 50 to 80% silver and silver in any language is a good thing. Check coinflation.com for exact dates.
Sincerely, Garoulady