You now have your store setup, but can you give customers a bill and receive payment?
If you’re working under a corporation, you may be required to use a specific program.
If not, you will have many more choices to make.
You can stick with paper receipts, but they are hard to deal with with a larger amount of sales. It is not a bad idea to have a paper receipt available though in the even of power failure and you cannot connect to an electronic source.
Paypal and Square are both popular invoicing companies. They can be setup to accept cash payments. These companies also offer a credit card readers and have more advanced readers available that can accept swipe, chip inserting, contactless cards, Apple Pay, Google pay, etc.
If you use an ecommerce website, they provide the invoicing online. They sometimes can provide offline invoicing too and possible cash transactions.