If I understand you correctly, here are some thoughts . . .
First, use a custom format on your input cells:
Format>Cells>Number
Category: Custom
Type: 0".00"
That will make the numbers look like they are rounded to the nearest
digit, but will still display 2 decimal places.
However...If you the sum of those cells to behave as if all of the
values ARE rounded, you'll need a different kind of SUM function.
(Since they will contain the actual inputs (1.51 will look like 2.00,
but will still be 1.51)
Try this for your totals (assuming inputs are in A1:A10):
=SUMPRODUCT(ROUND(A1:A10,0))
That function sums the rounded numbers.
Does that help?
Ron