[Henry17]

In theory you could but I don't know how many supernovas shop at Walmart. I know I've been in one twice in my entire life.

The extra 8% isn't worth having where you can spend the funds limited.

In theory I guess you could buy Pre-paid Visa gift cards and use them almost anywhere but those at least in Canada tend to have a lot of fees that would quickly eat into the 8%. They are also usually used by people with bad credit so there is that stigma which again is not worth 8%.