Not paid enough to say "no refunds" but given the ability to authorize giving out money for unofficial reasons? If it's unauthorized, then they're essentially stealing cash and assuming an extremely high risk of getting fired to avoid confrontation.

I've never worked a gas station, but I've worked fast food and I would have been fired soooo fast if I were giving out unauthorized refunds. Maybe even prosecuted if the amount was large enough. I've seen people fired for less.