It depends on the pot size. If you just win the blinds, no tip (but maybe add $1 to the next tip you give). For relatively simple hands, where the dealer didn't have to count stacks or manage multiple side pots, I usually tip $1 or $2 per hand. Maybe a $5 chip if I win a particularly big hand (generally 100+ big blinds) or multiple pots in a row. If the play of the hand is complex and the dealer does well at it (efficiently counting down stacks, building side pots well, etc), I add a $1. For jackpots, I tip between 5 and 10% of the prize ($50 on a $500 high hand, $100 on a $1500 royal flush bonus). The average tip, per hand and excluding jackpots, probably runs somewhere between $1 and $2 overall, from what I've seen while playing.

@Tthaas ,, what are you tipping for ? They don't shuffle the cards ,