If your customers need to receive a cash receipt after they make a purchase you can either print or send them a receipt from Billdu.
To create a cash receipt, you have to add a payment to an invoice first. Take a look here to learn how to add a payment.
Select an invoice
Swipe up the action sheet to bring up a menu
Select Send Receipt
A preview of a receipt appears
Click on the icon on the right to Print or Send
Select and preview an Invoice
Add a payment or a partial payment
Click on Create button in the upper left corner
Select Cash receipt
A PDF file will be created and downloaded
The sum and date on the cash receipt will be equal to what you've added to the payment