Cashiers Are Not Paid Enough For These Questions

I work at a store in my local mall that appeals to alternative and geek culture. A family comes in: grandma, mother, and daughter. The daughter is maybe in her early teens, bald, and basically, the typical teenage girl who shops at our store. They walk around for a bit and I notice that the daughter keeps excitedly pointing out things she likes and her mom and grandma keep shooting her down.

They finish shopping after about forty-five minutes and come to pay. I ring them up and the mother and grandmother are visibly displeased with the total (as if they didn’t know the prices of what they had grabbed) and the girl looks kind of uncomfortable, but then she drops a bomb on me.

Girl: “Um… Do you have a cancer discount?”

She’s looking at me with the saddest little doe eyes, as if a sixteen-year-old being paid minimum wage at a massive corporation has any say in the price of things.

I am totally taken aback. Her mother and grandmother don’t interject whatsoever. How do I answer this without looking like an a**hole?!

Me: “Umm… no, I’m sorry.”

Luckily, my manager overheard and turned around to quickly take care of the situation. He was livid when they left. I have a sneaking suspicion that the mother and grandma were telling her to say that to guilt people into giving them a discount.