Wrong scoring system

How many times have you seen a gaming review site give a score of 3.5/5 (3.5 out of 5) or something similar? Aside from the fact that it just looks a little odd written down like that, it strikes me that they are "breaking a rule" of their own system.

Surely the original intention of choosing a five point scoring system was that they would only ever be giving scores that were in fixed large increments? If there are regular reviews with .5 increments, I can't help but feel that the site should have chosen to go with points out of 10. The 3.5 would then become 7/10, which just looks better on the page to me.

Of course, I've also seen sites which give scores like 8.4/10, which suggests to me that they should be using a percentage system...