Fees when you sell an item

[retro-connection]

I just did the math on the amount of money I received after the fees were taken out.  It looks like they add everything up, including the tax that they collect and charge us a fee that also included the tax. 

Here are my figures: 

Item subtotal$37.00

Shipping$3.50

Sales tax (eBay collected)$3.34

Discount$0.00

Total**$43.84

So take the 43.84 (this included the tax)

                      -12.35% = 38.43

Take the $38.43 - 3.22 (actual shipping cost) - .30  - $3.34 (tax) = 31.57 (ebay deposit into my bank)

So does that mean that we are charged a fee which included the tax (which they send to the state) and shipping  and then they subtract the tax and shipping and the end is what they deposit. 

Does that seem right?  We are charged a fee for shipping (like it's revenue) and the tax (they collect) and then they take out what the shipping really cost and the tax they took out.   (I think I repeated myself twice, but how can they do that)?