The Gross Sales tile adds up the product subtotal before discounts of every order placed in the date range. It does not include taxes, delivery/pickup fees, bag or service fees, or tips – those each have their own tile. It also does not subtract coupons or refunds: refunded and unpaid orders are still counted in full, and the refund amount is shown separately in Total Refunds.

If you want a figure that is net of discounts, refunds and processing fees, use the Profit And Loss Report (Total Net) instead.