I think this varies a little bit according to the situation.
It's one thing to bink a $20k score at your local casino if you are a reg...
It's quite another thing to bink a $30k score at some casino you only play at once a year...
and quite another thing to bink a $60k+ score in a multi-day super huge field MTT
then throw in tournaments in which the rake is: A) heavy, B) medium, C) light...
With all that being said, I think tipping any amount around 1% - 2% is fine. Truth is, no matter what amount you tip everyone is going to think you should have tipped more. Everyone is always more generous with money that isn't theirs. I'm always amazed at how someone will tip what I think is a decent tip and then others who busted out are quick to say, "You should have tipped X amount more!!!"
And truth be told, memory spans on tipping are gold-fish short. For the most part, most people do not know, remember, or care what you tipped and after a day or so it fades away anyways....