The following 3 month Bank of Canada US to Canadian Exchange Rate is a good rate to use making transfers outside of a bank. This graph is live and changes daily.
This graph also shows you the exchange rate trend so you can make a decision where you want to exchange your dollars from or to US.
Also here is foreign exchange rates from 3 of the main banks.
Scotiabank Foreign Exchange Rates
TD Canada Trust Foreign Exchange Rates
RBC Royal Bank Foreign Exchange Rates