"PA" wrote:
Does the Round function round the number of
significant digits stored in a cell, or does it round
the number displayed? I believe it to be the latter,
but need confirmation.

How did you arrive that (wrong) conclusion?

The answer is: ROUND() rounds the actual value in the
cell, not the displayed value.

You can convince yourself by conducting the following
experiment. Enter 4.49 into A1 formatted as Number
with 1 decimal place. It displays as 4.5.

In A2, enter =ROUND(A1,0). If you are right, A2 should
be 5. If I am right, A2 should be (and is!) 4.

Of course, if you had entered =ROUND(4.49,1) into A1 in
the first place, the displayed value and "the number of
significant digits stored in a cell" are the same (4.5), and
A2 will be 5. Excel has no memory of the precision of an
expression before applying the (last) function, which in
the case of ROUND() changes the precision. Perhaps
that is where you confusion arises.