Using discounts to encourage customer to purchase more or keep existing customers is part of the life of selling goods. AX allows you a few variations on setting up discounts. This is a quick walk through of setting up lines discounts in trade agreements.
Keep in mind this walk through is on the sales side there is similar setup that could be done on the procurement side. As well if you are exploring discounts you might want to also explore the additional discount features the retail module adds.