True story: I had stopped by a friend's auto salvage to talk awhile. A customer came in and needed four tires. Roger showed the tires to the man, "ten dollars apiece or I will take fifty for all four!" The man couldn't whip his money out fast enough. With my finely honed pool hall ethics I didn't say a thing until the customer left. Then, "Roger, you just sold the man four tires for more than you would have sold them separately."
"Yeah, I know. My hired hand did it one day and the customer liked it, been doing it ever since!"
My father in law went into a place that had a great deal on tires. They were advertising "buy one, get one" on their sign. He got charged for four tires and asked about the "discount". The guy said ... yeah, you buy one and you get one, you buy four and you get four... what's the question?