Joomla Site Install With Virtuemart Standard Install

We have a Joomla website needed set up as per the template.

This site includes VirtueMart (no products to be added by you) and must conform to the template (joomlart again with licence)

There is one extra requirement for this site.

As a example

If there are 4 categories, we need to be able to change the price via a % for either 1 category, 2 3 or all.

So, if we are selling say fruit

Category 1 apples
Category 2 pears
Category 3 bananas
Category 4 melons

If the price of melons goes up we need to be able to add say 15% to all the products in that category.

The template is standard, there is a module for the price increase requirement and we expect the site to be fully working with all the correct permissions