If you seldom use discounts, applying manual discounts might be the easiest solution for your Point of Sale.
You can either apply a discount on the whole order or on specific products.
Apply a discount on a product
From your session interface, use Disc button.
You can then input a discount (in percentage) over the product that is currently selected and the discount will be applied.
Apply a global discount
To apply a discount on the whole order, go to Point of Sales ‣ Configuration ‣ Point of sale and select your PoS interface.
Under the Pricing category, you will find Global Discounts select it.
You now have a new Discount button in your PoS interface.
Once clicked you can then enter your desired discount (in percentages).
On this example, you can see a global discount of 50% as well as a specific product discount also at 50%.