I know it's lunchtime and you are extremely busy.. but..
If I had known you were going to show such disdain for me because I wanted to use my $5 gift certificate and then pay for the rest with my credit card, I would have saved the gift cert. for another day when I was the only one I was paying for and it would have covered the entire cost. The fact that you got all huffy with me, and looked as if I had insulted you or something was pretty uneccesary.
Also, I tend to like to think that conversing with customers is standard practice for most businesses. If you can't be bothered to even say one word to me, then I don't think you need to bitch to your coworkers in spanish while I am there. I might not understand most of it, but your tone said it all. I don't know why it's MY fault and I should be the bad guy because you don't know how to properly ring up my payment.
You had to ask someone how to properly ring up my payment, which I don't mind at all, but lose the damn attitude.