Do Canadians prefer US Dollars for tips? (Or as long as you tip, who cares ...)
It doesn't matter. Canadians will appreciate either. You can use US money in any store too and then you'll get the change back in Cadadian - we even take American coins.
Canadians from Montreal dont tip. kidiing...kind of.
I can guarantee you that when you tip in U.S.$ in Canada. The store owners, servers. and other staff will hoard that U.S.$ for their trips south....I Know. Because my wife does that.
All tips are good and with the current exchange rate tips in US $ do go further.