Changes of the prices by categories

-- url of the page with the problem -- : kosmima-gkiotli.gr
-- HikaShop version -- : 2.6.1
-- Joomla version -- : 3.4.8
-- PHP version -- : 5.4.45
-- Browser(s) name and version -- : firefox 44.0.2

Hi,
I have made a jewelry store with hikashop for someone else. So, because the price of the gold have increase or decrease my customer want to have the ability to change the prices of golds products depending on the percentage of the price changing of the gold. For example if the gold have increase 10% my customer want to have the ability to increase the prices of his products by 10%. I know that you give us the ability to make discounts on categories or on products. So, is there any way to make something like converse of the discounts when it is necessary?

Thanks in advances

Sorry for my english, it is no good, I believe that I have found the solve by the mass action. I wanted to increase the price of products on specific categories when the gold has increase price. I think that I found the solve, thanks for your response.