I created a round brush (download this image to your brush folder in the AS or Moho directory):
And used it on corners and ends of strokes. One of the drawbacks is having to use it on a "second" shape since if you put it on the whole stroke and stretch out the points you get spacing of the brush.
I discovered a new trick while doing some whiskers. I wanted to have those round ends but needed the ends EXACTLY on the end so the round part stays in position relative to the stroke.
I add an extra point on the very end. I peak BOTH POINTS. I create a regular stroke shape for the WHOLE path, then select just the last two points and make a tiny stroke shape there that will use the custom round brush.
Next just move that last point to sit exactly on the point behind it (Since there are only two points they won't weld).
No you can push and pull and twist that stroke all over the place and the tip will always maintain a nice round cap end.
EDIT:
Make sure both points on the end have the same width!
-vern