I'm not ignoring you---I can't hear you

Tonight I went to the grocery store and did massive shopping. I despise grocery shopping. it's one of those thing i wish i could delegate to others. anyhoo, i get to the check out and unload everything onto the little conveyer belt for the attendant to scan. there wasn't room for the bag of potatoes so i held it up so she could use her hand held scanner and then i could just put it back into the cart. i stood there holding the bag for a minute before she noticed and then she scanned it and i put it down. i didn't think anything of it, that it took her a moment. then, i realize she is talking to me. i can't understand what she is saying and had to ask her to repeat 3 times before it got it. she sounded really irritated and said "you should have told me you were standing there." i was confused then realized that she was talking about when i was holding up the bag of potatoes. i told her it was not a problem but she continued talking, saying that i should clear my throat or something to let her know i was there. i was still having a problem hearing her b/c the grocery store is loud (especially with registers and scanners beeping, ppl talking, etc). I told her that i can't hear what she is saying because i am deaf. Ok, so slight exaggeration on my part. BUT, i am VERY hard of hearing in my right ear (childhood infection) and in noisy places I have difficulty distinguishing noises. After i said that I was deaf she started talking in a very loud and slow voice. I tried not to laugh. Then, she points to the total on the register screen and holds up her hands to show the numbers (like holding up five fingers and point to the number 5). I'm still trying not to laugh. The young woman bagging the groceries finished and I told her thank you, to which the woman responded for me to have a nice night. I echoed the same to her and I saw the cashier looking at me like "how did you hear her?" I just looked at the cashier and said "oh I read lips very well." As I left the store i thought about the whole exchange. Up until I told the cashier that I couldn't hear she was kind of snippy with me. Her tone changed and while she was trying TOO hard (by pointing at the numbers and holding up her hands), I can see that at least she was trying to be accomodating.
I am thankful for what hearing I have. I need to be more mindful and sensitive to people around me who might be struggling to hear or to see or to walk or to read. Being differently abled doesn't mean a person needs special treatment, just maybe a different approach.
Who would have thought that a trip to the grocery store would be such a teaching moment?