Doh! Okay, I get what you're saying now. I was finally able to get on Construct just now and test it out. I see now that N Angle is only a visual trick, the actual angle is still a full range of degrees.
That's really weird and counter-intuitive. I totally didn't expect it to behave that way, that's where I got confused. It seems to me that if you're locking the rotation to a set number of steps, it should only return those step values.
It's also strange to see your sprite display at exactly 180 degrees, but be told that it's really 185.9408654 degrees. It's like the angle of motion is tied into the angle, and it doesn't need to be.
Just checked out Jeswen's .cap. Pretty clever solution. Just an fyi though, you don't need to have an Always event on every line, it works just as well this way: