Hi viret56,
The only way that you can display numbers in the grid on a screen to the nearest 2 decimal places is by adding the field type of decimal to the table associated to the screen. Adding the field type of money will permit the user to display more then 2 decimal places on the grid while the decimal field type will round the number entered to the nearest 2 decimal (i.e 23.79) even if the user typed in 23.789 in the field.
I hope that this helps.
Ronen