Finally made it to Mariano's and it worked, but I was capped. My groceries were just over $37 and it offered me the option of $20/$40/$60/other. I choose other and entered $100 and it was denied. I redid it and choose $60 and was approved.
Nice little perk, I like it! Thanks again OP! 
Discover Cash Over is a lovely feature... but yes, places have been reducing or temporarily eliminating the amount avalible...
No rewards but also its treated as a normal purchase transaction, with no penalty Cash Advance APRs or fees...
I think i saw one store offer up to 150$ at one point... but the usual is 50-100...
-J
