Grocery King allows you to conveniently edit multiple items at once instead of doing it one by one. Some of the supported actions include the ability to copy items to another list's favorite, ability to assign aisle tag, ability to assign tax rate.
To Group edit, tap on the menu button as shown below and select "Group edit" from the menu. Now pick the items you like and tap on the action button to bring up a menu. The menu has multiple actions that you can choose from as shown below.