Since for all intents and purposes Storybrooke doesn't exist within the realm of the show, I doubt the Federal or State government collects any taxes from the locals. Perhaps when everyone remembered their past in the Enchanted Forest, they decided to adopt some kind of medieval "serfdom" economy, but that's very unlikely and has never been shown.
I imagine they do pay some kind of tax to maintain the town and that sort of thing. But where does the clothing/goods/food come from? Is it delivered from outside, or does it show up magically at the stores/shops?
We never see the other townspeople in the present treat Mary Margaret and David as royalty really.
Storybrooke is a fraud, and all the characters should be trying to get back to the Enchanted Forest at every opportunity. If the show had been a short miniseries, I imagine them all regaining their memories and moving back to the EF to be the ending.
But that isn't the kind of story the writers want to tell for a several seasons show.