Lowes sold me carpet and install. They demanded that I buy an amount of carpet that they determined that I needed. I did not agree that I needed so much (with 22% waste) and asked to be shown how they intended to use the carpet requiring the higher amount.
They refused and refused to install unless I agreed to purchase the higher amount of carpet that they said I needed. So I had no choice but to agree.
They said that this was something that was industry standard and required by law.