Once you have the item selected for the sale press the 3 dots on the right bottom corner

In cash write the amount they wish to pay from cash for instance from 106.00 they would like to pay 50.00 from cash write 50.00 and once you do you will see the blue button which was "Settle By Cash" to "Add Payment"

3. After adding the payment select the next option the customer wishes to pay the remaining outstanding amount 56.00, for instance from "Card" and press "Settle by Card"