I use these in my classroom as part of my "Working hard for the money" behaviour/reward system.
The students earn money for coming to school, finishing their work, staying on task and other incentives. They use this money to pay rent for their desk and chair, pay for extra stationery items such as pencils, glue sticks etc. They also get fined for things too such as not being on task, etc. The students get their pay at the end of each week minus any fines and rent.
The students can use this money to buy things from the "classroom shop" or save their money for something else later in the term/year.
I print each money template on a different coloured paper (purple $5, blue $10, orange $20, yellow $50 and green $100) to match the Australian note colours. Then I laminate them and cut them out ready to use.
My students love this idea and it has worked well in the classroom for the last 2 years.
These could also be used for maths centres and games.