Not 5% for everything, but "5% in our store" are common (Amazon, Best Buy, Lowes, etc.) and of course tons of cards do categories, so I can't exclude the case w

Not 5% for everything, but "5% in our store" are common (Amazon, Best Buy, Lowes, etc.) and of course tons of cards do categories, so I can't exclude the case where however the service is classified (I have no idea... is there a category for government payments?) it fits one of the categories. In fact, some card might even run it as a promotion - with suitable limits, it's no more expensive than any other 5% deal...