I'll tip a dealer, on a cruise ship, if they make an effort to make the game enjoyable. I like an interactive and fun table. If I win I usually tip about 10% of my winnings. I have tipped even when I've lost if the dealer(s) let me have fun while I gave them the money.
I wouldn't even think about tipping on a slot win. The machine can't pay out the winnings, or the jackpot needs to be verified, so an attendant is basically giving you the money the machine should have paid.
Take care,
Mike