The Backstreet Boys are having a blast during their residency at the Sphere in Las Vegas - and apparently raking in the cash as well. According to a Thursday, August 28, report from TMZ, the boy band is grossing $4 million per night for each show held at the Sin City venue. The outlet notes that costs are somewhat lower for a residency than a traditional tour, as the group doesn't have to factor in so many travel costs when they're staying in one location.