Guild Wars 2

So i know that to sell an item, the TP will take away 10% as tax and another 5% for listing fee that make it 15%. Let say you sell one item for 1 000 000c which is 100g (1g = 10 000c), subtract 15% you get 850 000c which is 85g. Correct?

Today i tried to sell 250 pumpkin for 37c each. if we do the math, without calculating the tax i should get 37 *250 =9 250c which is 92s50c, if i subtract 15% tax from it, i should get 78s62c. But base on the number the TP gives me, i will only get 77s87c. see the picture.
http://i1227.photobucket.com/albums/ee440/dg2903/tp_zps3ccfaf72.png

What’s going on here? did i make a mistake while calculating?

10% of 37c rounds up to 4c so the Projected Profit uses 33c apiece giving you 82s50c instead of 83s25c. That’s worse case I believe, your profit if they sold off one at a time. The 5% fee is again rounded up to 4s63c but since you are posting all 250 at once it’s based on the 250 × 37c number.

Now I believe if someone buys multiple ones from you at once, it’s the total purchase price that gets 10% knocked off of it. So it someone buys 10 @ 37c, you will only lose 37c in tax instead of 40c. But worst case is 250 different players buy 1 each in which case the tax will be 4c.

There’s no tax on using the gemstore.. HINT HINT HINT HINT HINT