You'll need to reference to column value itself, not the cell. If your column is a calculated column, you can simply do this by doing:

=iif(Fields!CalcColumn.Value = 0, TRUE, FALSE)

If your column has the formula in it, you'll need to put the formula in instead, for example:

=iif(Fields!PreTaxCost.Value + Fields!VAT.Value + Fields!ShippingCost.Value = 0, TRUE, FALSE)

You post above also implies that you're attempting to do this outside of the data group, which can't be used to hide individual rows, unless you're planning to hide a whole group.