I used to cashier all day, and my feet ached. I never did find a good shoe (but I never tried any of the really expensive ones, because, well, I earned a cashier’s wage). I found that some relatively cheap shoes (like the Dr. Scholl’s ones) did okay as long as they were replaced frequently. My coworkers also recommended Skechers, or Birkenstocks if you can afford them.
It makes a difference if you stand all the time or if you are allowed to walk around. Walking is at least something the feet were meant to do, while standing in one place isn’t – and this distinction should inform the choice of shoes.
The only thing that really helped my feet long-term was getting inserts from a foot doctor. She took a cast of my foot and they made the insert to fit my foot exactly. These worked, not like a charm (because they still hurt), but it was better than anything else because they didn’t hurt so bad or for so long.
After thirteen years of standing, I quit – and that provided the best relief. ;) They still hurt more easily though, and I haven’t cashiered for more than two years. I think they just get broken after you stand for far too long.