Threshold (amount-based) discount in Dynamics 365 for Retail(Commerce)

A threshold discount is a discount that is given to customers when the total for a transaction reaches one or more specified amounts. For example, you could create a discount that gives a 10 percent discount for purchases over 100.00 and a flat 25.00 discount for totals over 200.00.

You can set it up from the following path Retail>Pricing and discounts

Once you have configured the discount as per your requirement as  shown here, do make sure you add a price group to it which has the the store mentioned where discount would be applied

On POS whenever you sell an item from the Jewelry category and if the total bill is going over 1000$, customers will get 5% discount.

Hope this helps!