I worked for close to five years retail, and generally, as stated in previous posts, the only customers that throw out that line are ones causing trouble.
Generally it's safer to say 'The Company's policies are always right.' They are your shield, an aegis to be used defensively and offensively when needed. As long as you follow the policies in everything you do, you will excel in customer service.
It's actually somewhat fun, playing with a belligerent customer. (Usually,) the moment someone walks in with a bad attitude, they are trying to get around a perceived policy, for example, returns without receipts, unwarranted discounts, price-matches for items that can't be price matched, etcetera. If you can find a way to use the policies to get what they want, a lot of these angry people will end up pleasantly surprised and leave happy. If you cannot, well, you still have your shield. They got a problem with it, have them go further up. They can't hurt you if you are behind the shield of company policy.