I take my bikes into stores all the time (when there is no conveinent/safe outdoor parking). I never ask, I just do it. Sometimes I get funny or curious looks, but I have never been challenged. Its amusing to me how people to not try to stop you from doing anything/going anywhere as long as you act like you belong or its not abnormal.

If I were challenged or told I could not park it inside, I would either (1) tell them I'd simply take my business elsewhere; or (2) ask them if they will agree to be liable for any loss or damages to my bike while it waits outside.

dave