Not a "major" retailer, but a regional fast food restaurant / mini-grocery: Braum's.
I was pleasantly surprised when I went in one for dinner earlier this week and saw that they accept NFC payments, including Apple Pay. Why was I surprised? Well, if you're not familiar with them, they're stuck in the 1980s (yes, this commercial still airs).
Just what I need -- another reason to grab a sundae. Thanks for the update!