Do everything without whining, complaining or arguing. Every one has their own jar. Start off the week with a set amount of quarters in each jar. If they are caught whining or complaining, they lose a quarter. At the end of the week, they get the money that remains.
It can be hard to get my boys motivated to clean when they are both pointing fingers of who-done-it. This helps stave off such arguments and makes Mama happy!