It depends on the value of the merchandise you are shipping. If your merchandise values over $1,600 Canadian dollars you must include a NAFTA certificate if it is under you must include a statement than can be found here... https://www.ups.com/content/us/en/sh...ta_origin.html

There is more you can do to make sure you shipments to Canada never get delayed by customs. Call your UPS representative for more details.

To start you may want to consider not worrying about the currency conversions. Let your Canadian customers deal with it for now.

In the review section a few days back there was a company that dealt with currency conversions for Web sites... you may want to pm him for more details.