[AKQJ10]

I can't imagine that it WOULDN'T be for tax purposes, or at least that they wouldn't also have to collect it for tax purposes, if your winnings were over $600 (I think that's the threshold). But it sounds like you won about $250, no?, so that wouldn't make it to that threshold, so I have no idea.

I think 3-5% is usually considered a reasonable tip for a multi-table tournament, and I see no reason why that wouldn't apply to a sit-and-go. 8% would be a bit high IIRC.