Hair Cuts at Great Clips (or where ever) do you tip?

For a $15 haircut, I tip between 4-5 dollars. I think a $5 tip is even acceptable for a 20 dollar haircut. I had a $10 haircut yesterday (2 on the bottom and sides, 8 on top), and I tipped $4.

Bottom line, always tip for a haircut, even if it's just Great Clips.