Skip counting is easy to learn if you just add it your routine. If you do a circle time or calendar time do it then. Two minutes a day and she'll have it down in no time. You could do more complicated patterns and start addition and subtraction (I'd use manipulatives.) If she doesn't know the value of coins, you could at least start with that and lay a foundation for later.
I taught this to my kids when they were 4 or 5, and they still sing it today if they forget:
A penny is one cent, a penny is one cent
A nickel is five, a nickel is five
A dime is ten pennies, a dime is ten pennies
A quarter twentyfive, a quarter twentyfive.
