Soon it will be tax time - time for tallying capital gains and losses for last year. CRA gives you a choice of calculation methods that you can use in your favour:
"Report your gains or losses in Canadian dollars. Use the exchange rate that was in effect on the day of the transaction or, if there were transactions at various times throughout the year, you can use the average annual exchange rate."
CRA has handy tools for looking up the exchange rates on a particular day here (any day in the last 10 years), and the annual average exchange rates here (any year going back to 1995 - 2009). Monthly average exchange rates (which you won't need to use) and annual average exchange rates from 1997 to 2012 can be found here. To save you the trouble, the 2012 average exchange rate for US dollars is 1 to 0.99958008 Canadian dollars.
PS - If you need that accuracy to the 8th decimal place you obviously had some big gains or losses last year!