If you lose your grocery store sales receipt will the store give you another?

I had my niece go grocery shopping for me. I gave her a signed check. When she got back, she hurriedly wrote the amount in my checkbook. I am suspicious because of no receipt and her wanting to write this in my checkbook herself. When I looked at the amount she wrote in my checkbook I was shocked. I think she bought things for herself and put in my cart and then her vehicle and kept them. I can't prove it. I know she will say she lost the receipt. Will the store give me another one if I ask for it? How can I find out without asking her. She will not tell me what really happened.