Mark those products that are with any promotion
Products that meet any type of discount can be marked so that they can be grouped together when making the sale. So from iPhone, iPad, or Web: Products > select product > turn on the option in discount
When doing the sale
When the order is taken you may promote the products that are at discount by choosing the "Discount" line by touching the icon of categories on Sale > New Basket or Quick Sale > Select Customer > Product list.