Getting Rid of Change

So I’m waiting in line to get lunch at school and when I go up to pay for my meal I gave the lady four quarters, a dime, and a ten dollar bill. A lunch costs $2.10. She looks at it for what seemed like forever confused out of her mind until I go: “I get nine dollars back.” Did she not know that I gave her the quarters to get rid of them? Maybe thats why she’s a lunchlady.