Unexpected Loss of Thalers, when purchasing skills?

[NoxDeth]

Every time I buy an skill upgrade, for some reason I have to pay more then the text indicates.

For example, I started an new game to check this,
selected to use camping, swords fighting and hunting,
then when I purchased farming (275 thalers acc to NPC) I lost al my thalers (303) acc to my inventory screen.


I also noticed this in a earlier game, but I thought I had mistaken myself about the values at that time.
I lost about 200 thalers more that time as my end result was that i had 0 thalers left acc to my inventory screen
(I went to full screen mode around this time).