Select “Customs Forms” from the left side Menu and click on “Form” button

In “Custom Forms”, make the product “price” and “price” fields correlate to each other

Click on pencil icon on the “Price” field and select the category you want to map as shown in the image below

Choose the category for product field mapping and click on "Save" button

On the web catalog, when customer added more quantity to the shop cart, the total price also increased as per the level of quantity.