How to ask out a cashier at a grocery store?

I was checking out today at the supermarket and started talking to the person in front of me, and the cashier as well. She commented that she loves the hummus that I get, and we were joking around. The guy in front of me made some comment like, you guys have a lot in common you guys should go eat hummus together or something. She blushed, and I started to notice she was actually pretty cute. I wanted to ask her out, but I wasn't sure how (never been very good at that). I said something stupid like, if you ever want to go on that hummus date, I'd be open to it. She didn't say anything, which I took as a no. What could I have done differently? It seemed like we had some chemistry, but I just screwed it up on the execution.