Grouped pricing in Magento 2, 2.3.5 at the time of writing is used for Tiered pricing as well, and I just wanted to highlight some of the quirks which aren’t apparent in the documentation.

Grouped pricing works on all product types but in different ways.

Simple Products:
You set the group price and the quantity in the admin, and the price discounts are reflected on the PDP (Save to to X%) and in the cart and checkout.

Bundle Products:
You set the group price and the quantity in the admin, and the price discounts are reflected in the cart and checkout for all the products in the bundle. You only have the option for % discounts here, as the bundle total can change based on the selection.

Grouped Products:
You set the rules on the simples, and as you’re actually buying the simples in a different way, they’re added to the cart individually and prices work as they would the simple products.

Configurable Products:
Similar to grouped; You set the rules on the simples, and as you’re actually buying the simples in a different way, they’re added to the cart individually and prices work as they would the simple products.