if you made only contributions, and entering the true amount bothers you,
for year end value enter the amount of your contribution.
for distributions or conversions, the real value is needed on certain worksheets.
see dmertz answer above.
It's your own tax return with your own data on it so why the concern?
If you have a basis in IRAs, you will have to enter the year-end total value for any distribution or conversion,
and it will appear on Form 8606.
