To select which items have prices tags and which do not, firstly access the Item Details screen by clicking 


Find the item that you need to alter and click the edit button: 

If you want to NOT print a price tag put a tick next to Tag Supress Print, if you want the item to print a price tag, make sure the box is UNTICKED:

Don't forget to click the UPDATE button at the bottom of the screen once you have made any changes.