Dollar Tree review: Customer service / discrimination

Me and my family had went to the Dollar Tree in Smyrna off Cobb Pkwy. We had went to the check out with ONE item in my hand, to a register that the light was on. The worker (Margarita) was at the next register. I had asked if she was at that register? Thinking since the light was on. She stated "NO". I asked if she was going to be opening, she said "NO". We proceeded to go to the one line that was opened, filled with about 5 customers that happen to be African American, as well as Margarita was. The moment that we reached the back of the long line, she said loud "I can help the next person in line". Really, wow! She was very rude and laughed about it to the customer that went in her line and I heard her say that "I'm surprise those people knew English" I am American, Mexican decent. I was born in America and do not even know Spanish. I was very disgusted with her behavior and felt like she purposely tried to embarrass us in front of the customers in the store.