@henel - you can set this up using any discount app that leverages Shopify functions. Here’s a collection of a few by Shopify themselves.
Our team is building one such app called “Dollarlabs: Ultimate Discounts” which allows you to set up volume / quantity breaks per market. There are two types of volume breaks that I’ve detailed here, and both can be easily setup using our app.
- Volume breaks based on Quantity of item purchased, configured per market
- Volume breaks based on Cart Quantity of a collection of items - configured per market
Example of both cases are detailed below for a better understanding of the offer.
(Case 1) - Volume breaks based on Quantity of item purchased (calculated per line item)
5 qty - 5% discount in USA
10 qty - 10% discount in USA
Line item 1 – 5*$50 → $250 - (5% discount is applied and is eligible)
Line item 2 – 3*$50 → $150 - (no discount is applied)
(Case 2) - Volume breaks based on total quantity of eligible items
5 qty - 5% discount in USA
10 qty - 10% discount in USA
Let’s assume both items are part of a collection on which you want to discount if the user buys > 5 qty from the collection
Line item 1 – 5*$50 → $250 (Collection A)
Line item 2 – 3*$50 → $150 (Collection A)
Total items from Collection A > 5 - So 5% discount is applied on both lines 1 and 2.
Both these discounts can be setup on our app easily. And here are two screengrabs showing you the configuration for the same.
Case 1 - Configuration example.
Case 2 - Configuration example
The best part is that we also offer a widget that appears on the page and shows the per-unit price of the product at each volume break. Here’s a screenshot with a bit of text lifted off from our app listing’s images 
If you have any doubts / the issue is still open - feel free to reach out.
Thank you