Actually there is a way to do this in 3.0, and the same way exists in 4.0. Use a Simple Conditional Action just at the end of the actions to be repeated, with Stop Repeating Actions as the action. That tests the condition, and if true, the repetitions stop.
There is also a while loop for repeats, by putting a Simple Conditional Action on the Repeat itself. You can read about those in the Rule 3.0 writeup here: [Released] Rule Machine 3.0
My next project is all new documentation for Rule Machine, which will consolidate all of this sort of information.
