Second button from the top on the right shuts most of those things up in my experience. If not hit every button, usually one of them will work.
edit: speedway has gone touchscreen, so I wonder if there are ghost buttons then?
That's the line which, when crossed, I immediately boycott and use another gas station indefinitely, but I get the feeling that it's only a matter of time before they all follow suit.
But surely, “all is for the best in the best of all possible worlds” that our late-stage capitalism has so benevolently bequeathed us.