Yes. At the start of a workout, at the bottom of the page, you will be prompted to select the number of 3-minute rounds that you would like to complete. By default, the workout will consist of ten 3-minute rounds. To adjust the number of rounds, prior to tapping start, swipe the round selector at the bottom of the screen.
You can select between 5 to 15 rounds. 5 rounds are the minimum number of rounds that must be completed in order for the workout to be marked as complete.