Personally as a UK approach radar controller, when I ask you to report heading or to turn by a certain amount of degrees and then report the heading, I would be happy for you to adjust the heading to the nearest 5 degrees and report that.
e.g.
You are flying on the STAR, heading is 353. I ask you to turn right 10 degrees and report the heading. I would be happy for you to both turn to and report a heading of 005.