We discussed this at Tappara.co a while ago but it seems that we never reported it. The rounding rules give confusing results even in single-option polls when there are more than two options. For instance in a poll with eight votes, one option had received no votes, two had one vote, one had two votes and one had four votes. The system considered that no votes equals to 0 percent, two votes equals to 25 percent and one vote equals to 12 percent. The confusing part was that 4 out of 8 votes equals to 51 percent in this case.
Another example. After four more votes had been given, two options had received four votes, one had two votes and two had one vote. It appeared that 4 out of 12 (33.3 %) was rounded up to 34 percent, 2 out of 12 (16.7 %) was rounded down to 16 percent and 1 out of 12 (8.3 %) down to 8 percent. The sum of the percentages is 100 again, but I’m not satisfied at all. We manipulated this later in a test poll so you can see it in action here: KORJATTU: Äänestystuloksen prosenttiosuuksien pyöristys - Kehitys - Tappara.co
There is no perfect solution for this problem. I consider that the best would be to accept that the sum isn’t going to be 100 every time. Perhaps you could add a note somewhere which shows when you view results of a poll with more than two options.
Due to rounding, the sum of percentages might not be 100.