Tax calculated wrong

[Guest]

Hi,

 

I have been working on this for ages and cannot find a fix, please help :'(

 

I have a tax rate (vat) of 17.50%

I have a product worth 0.99

The price of the product including tax comes to 1.16325 (rounded off to 1.16)

So far this is correct.

 

Now to the problem,

 

If I have a quantity of 5, the VAT should be added on to the cumulative value (4.95) and should therefore give a value including VAT of 5.81625 (when rounded off should be 5.82) ((0.99 x 5) x 17.5%)

 

Instead the total that it is giving to the customers is 5.80 (1.16 x 5)

 

Basically it is multipling the quantity once the vat has been applied and rounded off, this is wrong and the vat should be applied after the pre-tax price has been multiplied by the quantity.

 

I need help with what changes need to be made to which php file, I have been looking for ages and cannot find where it should be. I came close with catalog/includes/classes/orders.php, but this does not change the displayed price when the quantity is changed in the shopping cart.

 

Any help would be very much appreciated