Sales tax for food

Georgia is a state where unprepared food is exempt from sales tax. My most recent order was charged $4.43 for sales tax when everything but a $7 item was food. I went through my previous orders because I've never seen a sales tax on any of my other orders (which were all paid with EBT) but this order was not paid with EBT. When I asked customer service about it, they refunded me $11, which was more than the sales tax, and when I went back and looked at the order, the person I talked to had refunded me for 3 items and never gave me an explanation of the sales tax. Has this happened to anyone else before? It just doesn't make sense for many reasons. 1. Why do none of my other past orders (which were paid EBT) have a sales tax? 2. Why was I charged the sales tax for food on the one order I placed with my debit card? 3. Why did customer service refund me for 3 items? 4. Why was my question about the sales tax never answered?