A minimum billable increment is not double billing when properly outlined in a contract. If one item is an hour and two minutes and is interrupted by a three minute item, the bill comes out to 65 minutes of work and 25 minutes of contractually obligated rounding. Anything that had to be item had to be rounded up to the minimum and that's the price the client had to pay for itemization. I wasn't going to play guessing games about which calls counted as an item and which ones didn't.