Coupon Tender at time of sale

ability to add coupons or vouchers at register for sale

IE: we hand out a flyer or online coupon or voucher.  A customer comes back with one and picks out his/her items. comes to the register and presents the voucher for x% or amount off the cashier scans the voucher with the other items  they bought. maybe the voucher is for just a free item so that item is discounted. or the coupon could be for the total amount of the sale.