I only tip in Canadian money also, and only with bills or by buying them a drink - which can be nice because you get to sit with them for a bit & talk, see if you want to go in the back later. Plus sometimes they’ll massage your shoulders or arms a bit, and/or let you feel their muscles.
I also find that the francophone dancers appreciate it when I at least try to speak some French with them. “J’aime tes bras” (I like your arms), etc :-) I don’t know if Americans and anglophone Canadians sound the same in French or not, lol (maybe I do, but a Texan might not? Haha)