I go with 6 and make them return them as they kill them. No cost to them for the uniform, but costs $15 per shirt when they quit / get fired if they are not returned.
Don't want any former employees robbing banks in my shirts.
If you don't know your costs, you can't bid right. If you don't bid right, you can't make money, If you can't make money, become a Wal-mart greeter.