Tax and discount setting in Magento

Question

Magento : 1.6 is My version.

I am facing some tax related setting issue and no configuration looks like working.

Here is the explanation. Tax on product 20%. Product cost 25(exclusive tax). On site all prices are displayed inclusive tax. Product cost inclusive tax is 30.

If 2 qty is purchased.

Here on cart page. 30 * 2 = 60 subtotal.

Discount 10%(calculated on Total) : 6

Want Tax to be on discounted price but it shows 10 ( should be 9 as calcuate tax after discount is set.)

Total : 54 this is right.

My problem is that on cart and elsewhere Tax is displayed as 10 where as it should be 9. I want to eliminate this.

Any configuration(didnt find one) or code modification will be ok.

Answer 1

Did you try back-end Tax settings? Under Sales >Tax > Calculation Settings:

    Apply Customer Tax -  Before Discount or After Discount
    Apply Discount on Prices - Excluding Tax or Including Tax

Answer 2

For My above question I looked into various post. Also I did go through magento code.

Finally after going through a post by Alan storm I conculded that If one wants to achieve results as per My query then following should be done: 1. Set tax exclusive. 2. overwrite all blocks so that at needed places tax is displayed as inclusive but for magento calculation it is exclusive.This alone will give result as needed. 3. This means overriding lots of blocks with magento.