Hi Central, I too do this, i find if you pay a good % you can retain better staff, if they get a low % they soon get bored, and you have the problem of re training.
I had a guy work for me, out of the days takings i gave him 40%.
He was a fantastic worker, he now has a business of his own and uses a similar method.
The guy that works with me now is on the same basis, I know he wont be going anywhere, and I know I wont have to train a sucsession of new cheap staff.
Pay peanuts, get monkeys