Casio SE-S10 Operation Manual page 4

3. MAKING CORRECTIONS TO A TRANSACTION:
To clear the last transaction (before the subtotal key is entered)
press the ERR/CORRECT key.
To delete an amount after pressing the SUBTOTAL key, enter the
amount to be refunded then press the – key.
4. REFUNDS:
To refund items after a sale has been completed, you can turn the
key to RF mode then enter the items as you normally would to
process a sale.
Once the transaction is completed it is important to turn the key
back to REG mode, if it isn't then all further transactions will be
processed as a refund until the key is returned to REG.
5. TO GIVE A % DISCOUNT (e.g. 15%):
Enter the price of the item then press the department the item
belongs to.
Enter the amount to be discounted (e.g. 15)
Press the % key. This will display the dollar amount that has been
discounted
Press the SUBTOTAL key and this will display total amount due
6. TO GIVE A $ DISCOUNT (e.g. $5)
Enter the price of the item then press the department the item
belongs to.
Enter the amount to be discounted and press the – key.
This will display the dollar amount that has been discounted
Press the SUBTOTAL key this will display the total amount due