Hoping that someone here can point me in the right direction, and that this is actually a simple task (but one that has me stumped right now).  I have a solution that I have developed and would like to make better use of a Checkbox.  The checkbox would display the contents of a field that contains multiple options/accessories that we can supply.  For the sake of this question, let's say it's 5 options; Window Tint, Trailer Hitch, Floor Mat, Tool Box, and Sunroof.  Each Item would have a different cost.  What I would like to be able to do is have a field that calculates the total cost of the options that have been selected (could be zero, or all 5).  I've looked for help on checkboxes, but the help documentation was not of use to me.

 

I thought this would be easy, but I can't seem to figure it out. 

You don't want checkboxes. You want a joint able between the options and the main table. And add records as needed. Then you can store the price of the option in the option table. Then you can just sum the items in the portal once they've been added.

So you'll have 3 tables (at minimum). The join table should have the ID of the main table and the option. And you'll need to store the price of the option when creating the option join records just in case the price of the option changes later.