I bought new carpet and install for parts of my house, and it was installed today. When they showed up, they looked at everything, the lead pulled me outside to show me the roll, and explained that carpet is only sold in full rolls - I'd paid for all of it, enough to also do the two spare bedrooms. He said if I wanted to pay him some extra - in cash - they'd also clear out those rooms and install it there. I'm sure it was so they could keep the cash and not cut their boss in.
OK, that's fine.