My Safeway card is in an old (female) flatmate's name -- actually, I just type in the number from the landline on that apartment, from way back in the days of yore when not everyone had a cell phone. The cashiers nearly always look at the receipt to address me by name. They used to say, "Thank you, Mr. R------," to which I would kind of roll my eyes. They would stumble over her last names, and I'd tell myself, "M------ is fine, thanks," M------ being her name. Now they say, "Ms R-------." They still stumble over the name.
Congratulations, that's a big step. Something about the ordinariness of the grocery store makes it scarier than a lot of other situations when you are first getting out.