Great question, we usually have ways to make tasks like that easier.

In this case it is the Post dated Pricelist. This feature is located on the web portal, it's under Management>inventory classification> post dated pricelist

It's also available as an import, but I'll show it as a CAS function

Effective cannot be the same day - you must do it for a day in the future.

To select the items, press on the square with 2 dots to bring up the pop up. select the style you want to change the price on, search. Check the boxes of the ones to change (or select "Check all") and press Set Select Values to Key. Those items will populate the main page. 

Make your changes and save

Here's the wiki page:

The new prices will be available on the POS on the date specified.