Today's stupid question - How to update all products in a category by a percentage? Searched through the actions control instructions but doesn't look like anything there. If not in CE 1.9.x.x is there a recommended extension?
If I'm not mistaken standard Magento does not provide option to massively change product prices by %.
Since you are interested in extension, you can check Store Manager for Magento application that allows to increase prices by percentage, filtering products by category.
Here is the article on how it works (2 ways: with import and without) -
You can download 14-day fully-functional version from the link in my signature (no cc or paypal required).