I probably would have left a small tip but I wouldn't be concerned if I didn't. I used to pay $7 to my dog's groomer and left a $1 tip but, after a while, I started thinking I could easliy do it myself.
I mentioned it to the groomer who told me to buy the clippers and she would show me how. Nice lady!
Now I do it myself, have some extra cuddle time with my dog, and save money, gas, and time. Also, the more I walk my dog the less often I need to trim her nails. It's a win-win!