We had one of their stores too but it was about 12 miles away. My mother went there at least once a week.
Never had a Thrifty but we did have a drug store on the corner 3 blocks from the house. They had a soda fountain as well. I could get a big candy bar (a lot larger than one of todays), a comic book, a fountain drink and change back from my quarter. Yes, the quarter was 90% silver. That was what circulated at that time and I was still in dingle digits but I needed both hands to count the years.
At $17 melt value, that silver quarter might still get you a comic book, candy bar, fountain drink, and change. (Not sure; it's been a long time since I've bought any of the three...)
That's interesting, I never heard of it, a 1930's marketing ploy, certainly unusual! Here's a neutron irradiated dime, something similar but different!