Update:
I called PA as the bookstore. They said retailers receive a 40% discount plus shipping (unless the retailer has a UPS or FedEx account). Typical. Don't know where the "only 5% discount" info came from unless I missed something.
I said it. I worked at a bookstore until recently, and the only PA book that came in while I was doing receiving had an invoice that showed a 5% discount.
ETA: If there's technically a 40% discount but the books aren't returnable, that's useless too. A bunch of vanity/subsidy authors got the bright idea of special ordering their books at bookstores but never showing up to pay for those books when they came in. The idea was this would force stores to shelve those books for sale, since they weren't returnable. Stores caught on, and now most won't special order POD books unless they are pre-paid, returnable (since the store may still have to take them back under most stores' published return/exchange policies) AND have a good enough discount (40% or more) to make the transaction profitable. At 5% discount, we were losing money by the time I unpacked the book, found the special order paperwork in the file, and called the customer, simply based on my time vs my hourly wage.
If you're wondering why I would be inprocessing a PA book after all that, it had been accidentally ordered by a new bookseller who missed the notations.