yes, penny machines can be converted to quarters (I do it with my machine at home). Quarters, nickels, and steel pennies can take a bit of a toll on the dies, though.

You'll see quarter machines typically charging $1 plus the quarter you roll (Disneyland is only 4 quarters total). In the past that was a problem for families trying to keep kids happy, but penny machines are transitioning to the $1 price point in many popular tourist locations these days