Hannah,
Thank you for the reply above. However I think there is some confusion here.
There is currently a difference in how WooCommerce treats a coupon and a regular sale/discount.
Say we have a $100 item.
If you have a 10% off coupon for this item, in the order export data you will see that the Order Total = $100, Order Subtotal = $90, and Order Discount = $10
However, if I have the same item on sale for 10% off you will get the following in the report.
Order Total = $90, Order Subtotal = $90, Order Discount = $0
This leads to confusion in the order export data, as it is not correctly showing products on sale as being discounted.
I believe this is what Manju was referencing above. The financially correct way count this data is to count items on sale as discounted in the same way as a coupon. The linked Stack Overflow article only touches on coupon generation, but does not get into how sales data is treated in order exports.
Thank you,
Nick C