Location of tax calculation in source for Shopping Cart

can someone please tell me 开发者_运维问答where the calculation of the amount of tax included in the total price of products is in Magento?

Im looking at /app/code/core/Mage/Tax but don't know where to look at.

Working with discounts calculates the tax wrong in version 1.4.0 and I desperately need help fixing this.

Sadly the original magento forum is kind of abandoned...

Greetz Spanky

You should be able to change the way tax is applied to discounted orders in the configuration section of your admin backend. There are options like "apply tax after discount" etc.