And where would you enter the dollar amounts for each selected value? You could define 4 separate number fields for the 4 check box values shown and use a script to look up and enter the dollar amounts from a price list table, but that approach does not work very well as it will result in problems and complications as you add other features and/or make changes to your design in the future.
Use a portal of releated records instead of a single field. Select a menu item from a pop up menu or drop down list instead of clicking a check box and a looked up value setting can look up the price from a table of prices and settings.
This then becomes the typical invoicing system you'd use in FileMaker and also in other relational database systems.
Typically you use at least 3 tables for this:
Your layout refers to invoices and a portal to lineItems is where you'd select the items. Products is where you'd record the current price for each item.
Here's a demo file that uses this approach that you can take a look at: http://fmforums.com/forum/showpost.php?post/309136/
As far as I know, this is still a Filemaker 11 and older file. If you are using FileMaker 12, launch FileMaker and use Open from the file menu to open this file to get a copy that is converted to the .fmp12 file format.
Please note that it IS possible to use the structure I am recommending here and have a working checkbox group where clicking an item selects it, creates a record in LineItems--with the appropriate price looked up, but this takes some more design work--including writing a script.
Thank you for this answer. I'll have a play around with it and see if I can get it to work.