Where do the halves and quarters of karma points come from, as well as the rarer fractional numbers?

Question

Habr

Right now, the indicator in my profile shows 35.7 points of karma.
If you look through the Habrahabr API , it shows a slightly more accurate value: 35.75 karma points.
This value behaves exactly like 36 points of karma, i.e. it gives me 36 votes for karma, topics and questions and 72 votes for answers and comments.
However, it is ¼ point less.
I became curious why this is so. Doesn't the voice of each of us mean exactly +1 or exactly -1 to karma? Where then do the half shares and even quarters of karma points come from, which abound in karma indicators in the list of Habrahabr bloggers?
(And not only half and quarter ones. XaocCPS hasthe fractional part of the karma indicator is 64% of a point, and for yoihj it is a tenth of a point.)
What is it: if a registered user gets into habbit and (or) trolls (or) in read only, does the weight of previously cast votes change? Or is the weight of the vote affected by the addition of the user to the watchlist of the recipient of the vote (and not vice versa, what good)? Or are user votes evaluated differently in cases where one of them previously invited another to Habrahabr?

Answer 1

For example, when my friend was banned, my karma decreased by 0.5.

Answer 2

http://habrahabr.ru/qa/30627/