Rounding with units

[Joe Horn]

Although it fails in Home, it works in CAS, so a workaround in Home and non-CAS programs is to use either of these syntaxes:

CAS.round(unit)
CAS.round(unit, places)

Only positive values for "places" seem to work. The usual option of using a negative value for "places" (to specify significant digits) does not seem to work. Values greater than 14 for "places" sometimes yield bizarre results (gotta be a bug).