Two answers.

See the above message which is correct.

There is no such thing as "Perfect Play" on a slot machine. The wheels spin, the pictures change, whatever it does, you have no effect on the outcome. With that, the percentages are set in the chip and as all have said, higher for a $5 machine, next a $1, then 25c, Etc.

The percentages on a Video Poker or any other game where the players decisions can change the outcome, the payback percentages are calculated on "perfect play". That Perfect play means you make the best percentage play for every given situation. In reality that means you would have to know hundreds of possible "correct" plays and have them memorized and actually play them, all the time.

Since most of the multi games will allow you to play from X cents to X dollars, and they are player decision games, the percentages are the same and don't need to be altered.

Example: a 9-6 video poker for 5c is identical to a 9-6 video poker for $5 a hand. Why? Because the percentages are part of the game design itself, the payouts and the probability of any hand coming up, not the machine.

By law the gaming machines in Nevada cannot know if you are playing one quarter or 50 quarters. Or one dollar or three dollars. (for examples) The machine is stupid and random and doesn't know how much you are putting into it.

The video poker machines don't care how much you are putting into it, the odds are calculated based on random cards coming up. The only effect the player has, and does have, is making bad plays and making the machine even more profitable.

I hope that explained it?