decimal totalSelected = 0;
        dataGridView1.Focus();

        foreach (DataGridViewRow row in dataGridView1.Rows)
        {
            DataGridViewCheckBoxCell cell = row.Cells[0] as DataGridViewCheckBoxCell;

            if (cell.Value != null)
            {
                if (cell.Value == cell.TrueValue)
                {
                    totalSelected += Convert.ToDecimal(row.Cells[3].Value);
                }
            }
        }
        lblTotalToPaid.Text = totalSelected.ToString("$0.00", CultureInfo.CurrentCulture);
    }