It depends on the details. You might find some guidance in NFPA 30, which has building codes requirements for flammable liquids. (I assume propane is included, but haven't checked.) Anyway, it spells out how much can be stored in what kind of building, how far separated from other stuff, etc. You might also be able to get some information from the local fire department or building permit people. There is also a Uniform Fire Code, but I think it mainly refers back to NFPA 30 for tank issues.
Around here, the 7-11's and other stores have outside storage racks of propane bottles for propane exchanges, so it's obviously done. But those racks are outsiden, not inside, and there may be a reason for that.