Discounted price for paying cash is the vast norm in and around Milwaukee.
It started at 6 cents, but now it's considerably more.
The most annoying part is it varies greatly between stations and it can be a challenge to find the 'credit card' price. Some stations display the cash reg., mid and premium prices, others display cash, credit and diesel, but not always in that order. And never clear enough to read as you drive in traffic approaching.
I paid cash for a while when the discount got better than my 4% reward card, but I don't carry that much cash and sometimes I'd forget to re-stock my wallet.
Now I just use my reward card, or the Discover card when gas gets 5% back - I just have to keep a mental log of which stations use a low cash price as a teaser.