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

I've been tipping $3-$4, but guess it should be more after reading this thread. I go to a barber shop two doors down from the Hair Cuttery I used to go to. Same price, shorter wait time, and ESPN on the big screen TVs rather than idle conversation about the weather. I do always feel like I'm overcharged though. After all, do you pay a landscape company the same price to mow the front yard of a town house as you would for mowing a two acre lot?