Apologies if this is well known, couldn't find any references to it.

It seems that setting a cell to currency format affects the precision
with which the cell's values are passed to VBA. For example:

Public Function TestDouble(dDouble As Double) As Double

TestDouble = dDouble

End Function

Then set cells:
A1: 0.123456789, formatted as currency, displayed to 15 decimal
points.
A2: =A1, displayed to 15 decimal points.

Precision as displayed shouldn't factor in, but is turned off just to
be sure.

TestDouble(A1) returns 0.1235
TestDouble(A2) returns 0.123456789
TestDouble(A1*1) returns 0.123456789 (!!)

Yikes. Is there any way to turn this "feature" off, so that formatting
a cell does not change the precision of calculations based on it? I
tried to find documentation for this behavior but didn't have any luck
there either.

Thanks...