OmniTrack offers an advanced option that you can use to modify the Purchase value that is sent with all Purchase events.

The standard value reporting sends the full amount that the customer paid with each Purchase event. So that includes the price for the products, taxes, shipping, and takes into consideration any coupon discounts that were applied.

It's very simple: The Purchase value shows what the customer paid at checkout.

If you wish, you can enter a percentage value in the advanced settings tab to report a reduced value amount instead of the full value (100% = default).