No Frills complaint: Embarrassed/Powertrip

I had decided to go grab a couple things at No Frills I used to like shopping there as I’m new to town and it’s convenient. So my sister my nephew and myself decided to go it might sound silly but we had made a bet to see if we all use different check outs who would actually be the fastest and come in first. So I paid at self check out my sister picked the second or third cashier and my nephew when to lane one.I had finished first so I went to check on my sister as the cashier started to give us the total I had put my bag of the items I had purchased into my sister’s shopping cart and proceeded to grab an empty bag to pack help pack my sister’s grocery and as I started packing her stuff my sister asked the cashier is she could pay half cash half debit and instead of being concerned with the person she was waiting to pay she yelled over to me ummm.. did you pay for those groceries I said are you kidding me of course I’m nit a theft and I come her all the time how insulting ans and embarrassing. And the worst part is after I had said of course I paid at self check out you can ask the cashier at self check out she demanded me to show my receipt and prove that the date is from today? I was so embarrassed and shocked very uncomfortable and I believe I was singled out in front off the whole check out lane because of my race it’s very disappointing and rude . I’m still confused as to why I was asked all those questions kinda like an interrogation I would like to say that I will be going back there but Atchison point I highly doubt it!!!!I didn’t even receive an apology!!!