What Should I Have Done Differently at Rite Aid Today?

I'll post the pic and details later, but I needed to get some Primatine Mist for my husband and thought I would try to get it as cheap as possible at Rite Aid.  I tried to get overage buying the Physicians Formula Bamboo Compact, using a $5 RA Physicians Formula coupon, and a $5 peelie.  I also used a 5/20 RA coupon.  I thought everything went through, I paid, and then discovered that only one of the $5 Physicians Formula coupons was on the receipt.  I think the RA one wasn't but the cashier never said anything about them not working and put both in the register.  I went back to ask, and by now the cashiers had changed.  This cashier told me that I couldn't use both because they are more than the cost of the item.  She said she couldn't adjust it down.  I asked to return it, and she said she could only give me $1.95 back, the cost after the coupon.  So I decided to just keep it and still do the rebate, so I'll get the 6.95 back.  What do you think happened?  Do you think this would have given me overage but the cashier didn't scan one coupon correctly and didn't notice?  I know that RA doesn't officially give overage, but I have gotten overage on things before.