I Eat Rounding Errors Like Yours For Lunch

I am working the checkout at the express lane. A customer starts unloading her full cart.

Me: “Ma’am, this lane is fifteen items or less.”

Customer: “Oh, I’ll be quick.”

Me: “You have more than fifteen items, ma’am, so you’ll need to go to the other lane.”

Customer: “Well, let’s just round down, shall we?”

Me: “Ma’am, rounding down could be a couple of items more. You look like you have over fifty.”

Customer: “We can keep rounding down until we hit fifteen.”

I close my lane and start to walk away.

Customer: “Where are you going?!”

Me: “I’ve decided to take my lunch break.”

Customer: “Lunch?! But it’s 9 AM!”

Me: “I’ve rounded down from twelve to nine.”

She went to another lane.