I get 30$ a week as an allowance and that money is coming from my tip money so that means 15$ a day of work minimum. So let say I get 25$ that day and the same thing the next day, I have 50$ and I have 20$ more than I need. I'm going to put the 20$ in my challenge money.

It's from my old rule but it works pretty good so I'm keeping it.

#4 : Put the "surplus" of my tip in my challenge money.