Math Is Essential

I stopped at Boston Market to pick up some dinner for my sister and me and the total order was $15.24. I gave the cashier $20.25. How come she counted out $4.98 to give me back in change? Then, when I alerted her of her error, she said that she punched the wrong amount into the register. Okay. Regardless, my change is $5.01. I gave her the .24 cents so I wouldn't get back a load of change and a bunch of ones. Math is essential, folks!