Let's say you have a multi-day rental and would like to offer a discount to your client for items that are rented beyond the first day. You can do so by adding Line Item Groups to a project, setting the rental dates, and then discounting the items in subsequent Line Item Groups.
For example, I have a three-day event and want to add a 50% discount to items rented on days two and three. Here are the steps you can take to easily create this in a project.
Add all of the items for the event to a Line Item Group
Change the date and name of the Line Item Group to match day one
Change the date and name of the Line Item Group to match days two and three
Navigate to the items you want to discount, click the three blue dots to the right of the item, and select 'Edit'
Add a 50% discount to each item and click 'Save'