depends on the teenager's age, I think. A 13 or 14 year old watching sleeping kids lie ... sure $5/hour. A 16 year old who now CAN get minimum wage jobs? Probably better to cap at $6/7.
What I don't understand at all is paying more than minimum wage for barely teenage kids. They just don't need that much. And what happens is then it's so expensive nobody asks them. My daughters understand this and wish people paid less each time, but asked them to do it more often. They would come out ahead overall, and people would get to go on more dates.