Anthony,
I think you need to change the dimension to a fraction, then it updates anywhere that dimension was used.
I cannot be sure about this, but I have done this in the past and it worked.
Use the Show / Erase dialog to place the dimension in a view.
Then, right click the dimension and change it from decimal to
fractional. Then use the same dialog box to Erase it.
Now, add it to the table to see if it changes to a fraction.
I noticed this in my part, where I changed dimensions to fractions on a
drawing and my part displays them as fractions in Part Mode. Once
you can see it as a fraction in part mode, you should be able to see it
as a fraction in the table.
I may be wrong, but this method worked for me in the past.
Also, make sure the dimension is not a parameter reference. I believe it has to be a dimension to show up as a fraction.
Jim