There are way too many steps involved in charging a client via tap to pay compared to stripe or square. Create a big button from the Home Screen, and have a dropdown to select the item (that has already been inputted) so the amount and GST auto-format.
(I don’t think this product has been tested enough to be released onto the market- the formatting is all over the place, words bleeding onto random lines and over each other- the menu items in top right corner illegible on iPhone 13… much more effort has gone into marketing than the actual app!)
also, allowing file formats for jpeg would be handy so people can send you screenshots of what they mean!