When I lived in Virginia Beach I got stuck with Canadian coins all the time. I'd try to pass them off ASAP but sometimes they'd be refused. Living in San Diego, you'd think that Mexican coins would show up occasionally. I can't remember the last time I saw one though. It's probably because even in TJ the U.S. dollar prevails. When I took a trip to Rosarito all the prices were in Pesos but every place took dollars. Considering how the exchange rates are for Canada and Mexico I don't think anyone should "swap out" the coins. A Canadian quarter is not equal to a U.S. quarter!
When I worked at SeaWorld we accepted Pesos and Candian Dollars. We also took Francs, Marks, Pounds, Yen, and Australian Dollars.
I'm sure they probably take Euros now.