Well....it depends....My groomer owns the shoppe, so when she does my 3, no I dont tip her as all the money goes to her anyway, but, If she has one of her students do one of my dogs, then yes they get a 10-20% tip.
My own hairdresser owns the shoppe as well so I only tip the shampoo girl unless hes doin an entires days work on me!!! lol Then Ill flip him something extra but only if he buys lunch!!! lol