I think there’s maybe a third option: for polls which allow users to select more than one option, change the presentation of percentages so that they just use a basic round() call, rather than whatever’s going on at the moment to make single-choice polls add up to 100.
I agree that we don’t want too much visual noise – I already hide the total number of votes through CSS (as that really is visual noise – if you really want to know it, you can do some pretty basic maths to find it!) – so I agree with you, @Mittineague, that showing decimal values wouldn’t be particularly useful.