Yes, I did do a very small test - 1 quarter roll and 2 dime rolls just to see what it was like to go into Canadian banks with US dollars, etc. First thing I noticed is the rolls are considerably smaller than US rolls as the coins are thinner. Second, I was surprised - and I guess I shouldn't have been, that there were US coins in there. I did snag one silver canadian dime (1963) so was pleasantly surprised.
However, the whole time suck (45-60 mins each way) of going across the border and back was a pain. I wasn't totally convinced it would be worthwhile to make a frequent trip of it, and I live just 90 mins from the border.