With mapping function, you can create the correlation between different variations. 

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

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

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

After the category is selected, click on the "Save" button to save the changes.

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