There is another option in Selbuk to create a sale. On the Dashboard there is a cashier icon. Touch it and make a sale 

Dashboad > Retail Mode

Touch Categories

All Productos

Select your customer from the pop-window

There are some things you should set on the Retail Mode Touch the Settings icon

Touch the magnifying glass icon to set the fields to search for

Now Select and item you may change the quantity on the plus sign

or you may touch the quantity and enter a different amount from the keyboard

If you touch the price tag, you may chose the one you need

If you need an additional discount on the sale, touch the label to enter it by money or percentage

Touch the Pay tag to chose the payment method

Touch select to pay exact amount then Finish Invoice

Touch ok to confirm the sale

Touch the lines icon to see the order/invoice

There you have on the screen the sale