Issue relating to when VAT is calculated/applied

-- HikaShop version -- : 2.4.0
-- Joomla version -- : 3.4.1
-- PHP version -- : 5.4

Hi, we have a shop that a variety of stock with a few that have small prices such as 0.09 each and the timing of when VAT is calculated with these is causing an issue.

The site owner prefers that the price of items are displayed on the site without VAT, as for larger priced items the perception is that they are cheaper even though the prices are declared as "excluding VAT".

Using the example above, an item costs 0.09 excluding VAT and is displayed as such on the website.

If you buy one of those items the cost including VAT would be:

0.09 + 20% (0.018) = 0.108 which will be rounded to 0.11

Using this method, if you buy 20 of these items the total including VAT works out to be:

0.11 x 20 = 2.20

However, if you take the price, excluding VAT, to be 0.09 and want to buy 20, the total for that works out to be:

0.09 x 20 = 1.80

If you then add the 20% VAT it would be:

1.80 + 20% (0.36) = 2.16

So, you can see in the above there is a discrepancy of 0.04 on the purchase of the 20 items which is caused by when the VAT is calculated. Hikashop is calculating the VAT on the single items so the total for 20 of them including VAT is 2.20, whereas it Hikashop calculated the VAT on the 20 items as ordered, then the total for them including VAT is 2.16

We recently made a change to the site to turn on the "Round prices during calculations" option in the taxes configuration in order to overcome an occasional rounding problem being caused by the way Paypal calculated VAT. Is this option now having a knock on effect to the timing of when VAT is calculated? I hope not.

I think it is correct that VAT should be calculated and applied to the total of each line item and not on an item by item basis, but Hikashop is doing the calculation item by item.

Please help with this - thank you