If you want to apply a fixed dollar discount against a gift card purchase, create a coupon entry (non-inventory item) with fixed negative value. If the discount will be a variable amount, select ‘Must enter price at POS’ under Options tab instead.
The item lookup code should be something simple such as PROMO101 or P101 so it can easily be entered in POS.
When the fixed amount coupon item is sold in POS, the negative value is deducted from the sale.
If 'Must enter price' is enable for variable pricing, the cashier must enter the NEGATIVE value to deduct from sale such as -10 for $10 off.
If the price is not fixed, You could also enter a default value of -$X for the full face value, but cashier will be prompted to change the value when entered in POS. They will have to remember to type in a negative number. There is no tender requirement in this example.
Sell a gift card for $50.
On the next line enter the promo code with a negative amount such as -25.00 for 50% off or -50.00 if the gift card is being issued for free.
Tender as normal.
TIP: Also search the Knowledge Base for "groupon".