very peculiar. It seems that a custom format like that always wants to end with 2 zeroes. Must have something to do with Scientific Notation. If is possible to do what you want using cells formatted as text and then the following formula in a corresponding cell.
Code:
=MID(G1,1,7)&"-"&MID(G1,8,2)&"."&MID(G1,10,4)&"."&MID(G1,14,1)&"."&MID(G1,15,2)&"."&RIGHT(G1,4)
Now of course I put the number in G1 put you can put the value where you want and then change the formula accordingly.
Sorry this isnt exactly what you are looking for but we could also write a VBA script which will keep it in the same cell after you process the code or on worksheet change. Lots of options here.
Thanks