Just use any sort of reminder system to ping you once a year or once every 6 months of whatever, to take out your stack of cards. Then when doing groceries or whatever, charge one small item to each card (only one such card per visit), until you've gone through the whole stack. Then put the stack away until the next reminder.

Something like that is how everyone used to do it before online stuff. And it still works. It sounds like a whole lot more trouble to try to set up things to make it be 50 cents when 2.10 would probably matter just as little (to any other cards you need activity on for points/miles/cashback/whatever reasons). And there's probably grocery or other items you buy often enough that are just a buck or two each, and it's easy at most registers to split your purchase with some items with one form of payment and other items with another form of payment.

Or, use the same method to pay some utility online. I regularly pay a few bucks with one card (that needs N separate purchases in a period of time to activate some bonus) to my cell phone or internet account, then go back a few days later and pay the rest (or just some more) with another card. The typical utility won't care if a couple times a year you divide up your online payment into 11 parts (10 small for these cards, 1 bigger for the rest).

But if the PayPal thing really works for you for 5 cards, you can just apply any of those techniques to the other 5.

Ie, I find that if I do all such cards in one time period every year (I don't bother more often than once a year), then it's no big deal to it "manually", and then not have to worry about setting up automatic billing that's small in amount yet rare in frequency.