[TYPO3-shop] unexpected tax calculations

[John Nicholas]

John Nicholas wrote:
> I'm using 2.7.0
> 
> I'm in the US so taxes are not included in the prices. The sales tax for 
> my state is 8.25%
> 
> I have plugin.tt_products.shipping.TAXpercentage = 0 and 
> plugin.tt_products.payment.TAXpercentage = 0
> 
> I have 2 products in my basket, 1 at $28 and 1 at $80. This is a 
> subtotal of $108 and my taxes show as $8.91 which is correct. I then add 
> another of the $28 items which brings my subtotal to $136. My tax should 
> now show as $11.22, instead I see $12.12. If I now add another of $80 
> items (for a basket of 2 at $28 each and 2 at $80 each) the subtotal is 
> $216, the tax should be $17.82 but shows as $19.63.
> 
> Any guesses what could be throwing these values off?

Turns out the tax is coming from the the "shipping costs for each 
additional item". For some reason tax is being calculated on the 
additional items. I didn't see it at first because I was only using the 
###PRICE_SHIPPING_NO_TAX### marker since I expected them to be the same.