A customer got upset at me because i had to refund her $0.01

I don’t know why she acted like i inconvenienced her when she made me look through her booklet of receipts. So the system in our store is that you have to get refunded the way you paid. She paid with a card. After doing her exchange, my computer says I owe her a penny. She didn’t like that we had to go through the whole process just for a penny so she tells me to hurry up and just give her receipt. I can’t do anything til I refunded her money so she gave me and the manager attitude about that lol.