To create roll-up summary field
Create a custom Salesforce field in Roll-up Summary Object. Ensure that the field is unique and multiple expressions are not used to populate the same field. This field comprises or holds the value derived from the aggregate expression in the Field Expression builder.
The rollup for a product is created successfully. You can navigate to the cart page and check whether the rollup is applied successfully.
After you create rollup fields for a product, you can re-use the rollups across products or within the same product by searching for the rollup, product, or product group name in the Search field. Drag and drop the requisite roll-up conditions that you want to use to the right greyed out pane.