Formatting only affects the rounding of decimal place display, not whole
numbers. IOW, if the cell is formatted for 2 decimal places of accuracy
125.777 would display as 125.78 & an entry of 125 would display as 125.00,
etc. Quite honestly, I'm not sure that you can regulate in that way even
with a Validation Rule.
The =ROUND() function can be used to display the rounded value but it
wouldn't regulate the number of digits displayed. Using your example &
assuming 12800 is entered in A1 you could have the this formula in another
cell: =ROUND(A1,-3) which would display a value of 13000 in that cell.
Perhaps someone else can offer other options.
HTH |:>)
Bob Jones
[MVP] Office:Mac