Hmm, I've actually never been told not to do this.
Is it considered poor practice to accept Canadian coins even if they make up a very small % of the purchase?
Never accepted anything other than Canadian, but I have never thought much of it if a guest hands me a canadian dime or two, the difference in exchange rates seems pretty much negligible, but I've never had a guest try and pay with Canadian bills, or pay for their entire purchase with Canadian coins.
It's in the training book that border stores that do accept Canadian currency have a button to account for the exchange rate, and that change is provided in American currency only. I live in a border state and honestly hardly anyone even notices Canadian change (I even tell Canadian guests that I can accept their change, that's how little people around here actually care). What happened at my store is that someone somehow accepted a toonie. :/ Americans don't even HAVE a two dollar coin!!
Yeah, I live in Michigan, we get a lot of Canadian coins, I have just always accepted them as if they were American. The toonie however, yes, I wouldn't accept that or a loonie, but dimes, nickels, quarters, meh. Every Canadian quarter accepted shorts my drawer by about two cents, I can't imagine anyone caring if a drawer is two cents shy of what is expected to be in it.