Am I just missing it or is there no way to do quantity discounts by percentage?  Doing it by exact dollar amount creates a lot more work every time there is a price change, so I prefer percentage - set it and forget it.  Please tell me this is possible.

Just a suggestion, but if it will save you any time.... When I have a mass change like that, I download the catalog list and do the manipulation in Excel. Then you can just save the csv and post back. Not saying it's a fix, just an option.