You might expect the 5-coin bet to pay $1000, but many slot machines pay out $1200 or $1500 in that case, trying to convince bettors to make the max bet. For instance, a 1-coin bet might pay $200, a 2-coin bet might pay $400, a 3-coin bet might pay $600, and a 4-coin bet might pay $800.
On many slot machines, the 5-coin bet pays out a higher percentage on the top fixed jackpot. Look at the payout chart on a slot machine to determine how jackpots are paid.