The third available option when Discounting is to create a Discount code that can be used internally when generating a Quote.
Simply go to Settings > Discounts > + New Discount to create your Discount Code
As shown in the example below, simply enter the Discount Code name, the chosen code to use, and select the appropriate Discount type (Percentage or Amount) from the dropdown menu. Additionally, you can choose if this Discount code will apply to recurring fees (if applicable) or just the up-front costs
Simply select the appropriate code from the dropdown menu when creating a Quote under the Discount section found above the Comments
When using a Discount Code, the Discount Code Name will be displayed under the Item column with the discount dollar amount calculated and shown under both the price and total columns as per the example below:
If you'd like to have the Percentage displayed, simply add the percentage to the Discount Code Name to have it displayed on the Quote.