C# rounding up or down in

How would I change this to round up or down ?

I have tried everything but the correct one.

Double, convert to double Trypharse, Math.Round Ceiling, Floor.

not sure where to add it.

Thanks

 //= AN2 * AO2
                decimal AN2 = Convert.ToDecimal(rows.Cells[39].Value ?? 0);
                decimal AO2 = Convert.ToDecimal(rows.Cells[40].Value ?? 0);
                var AP = AN2 * AO2;
                rows.Cells[41].Value = AP;

Booney440