When we had the Super Bowl pool at work the guy who ran it indicated that the winner should tip the guy running it. I forget the amount he suggested. They also run a weekly pool where you put $5 in and they pick the name from the hat. I asked the guy who runs it if he expects a tip. He was much more lenient about it. He said that not everyone tips and he refused to say the percentage. What is the standard tip amount if you win?