Not sure tip is the right terminology. We occasionally go out and use the services of a babysitter agency. They charge around £5 per hour and we book for 4 hours. The money is given staright to the babysitter. I am not quite sure how much she gets and how much the agency taked. Is it good practice to give her a bit extra? If so how much? I am never sure. The exact bill for 4 hours is £23.20 and I normally round up to £25 for convenience sake.