Square is most often pitched as heaven for small businesses, but that 2.75 percent cut per transaction is sometimes a problem for stores that are too successful. Enter a new flat rate option. Shops that don't take more than $250,000 a year in Square payments, or charge more than $400 in a given sale, can instead pay a flat $275 per month regardless of how many swipes they take. The deal makes the most sense for businesses handling more than $120,000 a year through the reader, establishing a definite limit to its usefulness; this isn't exactly for a budding jeweler (or Starbucks). Even so, the simplicity of the rate might be very alluring for companies that aren't keen on surprise costs or working out the math, and it's a contrast to the half-steps towards flat rates taken by VeriFone and other, more traditional outlets going mobile.