It's tax season in America. With the deadline looming to pay Uncle Sam less than a month away, many are wondering — or grumbling — about how their tax dollars are allocated in the first place. But now participatory budgeting, a concept in which citizens get to vote democratically on how a particular pot of public funds will be spent, has been gaining traction across the U.S. over the last few years, and promising to give citizens a voice in these matters.