I was working on a GUI that uses round avatars and I it was driving me crazy that the edges of my images were getting cut off by just a few pixels. (see the flat edges on the attached image)
After messing around with the 'fit to fill' settings for a bit with no success I discovered that I could fix the problem by simply adding a solid 0 point stroke to the container. What I also found interesting was that if I added a 'transparent line' it cropped the image in towards it's center and the stroke remained invisible.
Note: Round 'buttons' with images inserted into them do not have this problem.