Tipping at a casino is a personal decision, but it's generally customary to tip around 1-2% of the jackpot to the attendants who assist in the payout.
Tipping the person who brings you your money after winning a jackpot on a slot machine is a personal decision. There's no set rule for how much to tip, but some people choose to tip around 1-5% of their winnings. It's also common to tip based on the level of service provided.