Staff members signed up to be "customers" and my kiddos were beyond excited to go into their rooms and deliver. Students had to solve a task card (finding parts of a whole), each one was assigned to a specific teacher. Once they had the answer they brought it to the teacher. The teacher would pay them if it was correct, and would tip if they had positive customer service.
While each team had a teammate out of the room delivering, the rest of the members were in "overtime" earning extra cash for completing extra challenges. These tasks included long division, adding decimals and rounding decimals to specific places (but they had to remember our rule that when it is $ you round up to make sure the bill is covered).
I have a link here to my TPT if you want to check out the activity. :)