Once students are able to master the concept of counting to an exact price, I like to challenge them some more. Now, I might give them a price of $18 and they would have to pay with four $5 bills ($20) in order to cover the cost of that item. Tricky tricky! I have found that starting with $10 bills are the best way to introduce this skill, as it is easier to count by tens and a little easier to see how many more they would need.
HERE in my TpT store! (Color-in $1 dollar worksheets also available)