I noticed in my activity stream here on ecency that all of the point values are not whole numbers like your post said.
I stopped with the buying of points awhile ago since none of the approximate values for boosts ever really came true.
Approximate vote values calculated/come from all votes not only from @ecency but @good-karma, @esteemapp and couple other team accounts. It is hard to estimate them exactly that's why it is is approximate vote value, by the time you receive vote price of Hive might change or reward pool changes that affect the exact calculation and by the time payout happens that changes also, so we do our best to estimate as close as we can get.
On, interesting, i imagine that the approximately value is displayed higher that it's actually ?
That's why I think I'll mostly use them to promote my posts. For now it seems that the promoting tool is working though 😅