Discrimination at Walmart

The last few times I have shopped at Walmart I have been accosted as I leave the store by an employee demanding to see my receipt. Normally I would not take offense; however, I am white and the employee is an African-American woman who works there every Sunday and she does not stop other African-American shoppers and demand to see their receipts. In addition, I have shopped at other Walmarts and they do not stop you as you are leaving demanding to see your receipt. If this is a practice that they are going to continue then it needs to be consistent. Every single person should be stopped and have their merchandise counted (i.e. Costco). I feel that I was being singled out and discriminated against since I am white and the store is in a hispanic neighborhood. My father is a retired judge and we are looking into if this violates my civil rights.