I definitely have a conscience about this kind of stuff - I try to always give back wrong change, whether it benefits me or not, etc. - because while I don't literally believe in "karma" as it's usually presented, I do believe we reap the energies we sow, and besides, selfishly, it makes me feel better. But having said that, in dealing with businesses, I've sort of rationalized the difference between "honest human mistake" and what you might call "benevolent customer service". I certainly am not going to let a cashier take the hit to his/her tray because of a miscount in change; I can help him/her with that. But for example, I got a wrong CD once from a vendor on Discogs. When I contacted him about it, he acknowledged it, gave the refund, and said "keep the original disk". And I did, without compunction. I suppose I could have done him a solid and sent it back anyway, but he's a businessman, he can make that decision.
If I was in your spot, I would try to figure out if it was a mistake, or if it was "customer service" (I don't think you said, but it also depends on how much the difference between 525 and 14 is; if they are $7.50 a chip, I'm probably calling them. If it's $0.10 a chip, not a shot.)