ต้องการคำนวณราคาค่ะ คำนวณราคาจากข้อมูลที่แสดงใน gridveiw ค่ะ asp.net c#

OleDbConnection objConn;
OleDbCommand objCmd;

double sumTotal;
public void Page_Load(object sender, EventArgs e)
{
	string strConnString = null;
	strConnString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + Server.MapPath("database/mydatabase.mdb") + ";";
	objConn = new OleDbConnection(strConnString);
	objConn.Open();

	BindData();
}

public void BindData()
{
	string strSQL = null;
	strSQL = "SELECT * FROM customer";

	OleDbDataReader dtReader = default(OleDbDataReader);
	objCmd = new OleDbCommand(strSQL, objConn);
	dtReader = objCmd.ExecuteReader();

	//*** BindData to GridView ***'
	myGridView.DataSource = dtReader;
	myGridView.DataBind();

	dtReader.Close();
	dtReader = null;

}

public void Page_UnLoad()
{
	objConn.Close();
	objConn = null;
}

private void myGridView_RowDataBound(object sender, GridViewRowEventArgs e)
{
	//*** CustomerID ***'
	Label lblCustomerID = (Label)e.Row.FindControl("lblCustomerID");
	if ((lblCustomerID != null)) {
		lblCustomerID.Text = e.Row.DataItem("CustomerID");
	}

	//*** Email ***'
	Label lblName = (Label)e.Row.FindControl("lblName");
	if ((lblName != null)) {
		lblName.Text = e.Row.DataItem("Name");
	}

	//*** Name ***'
	Label lblEmail = (Label)e.Row.FindControl("lblEmail");
	if ((lblEmail != null)) {
		lblEmail.Text = e.Row.DataItem("Email");
	}

	//*** CountryCode ***'
	Label lblCountryCode = (Label)e.Row.FindControl("lblCountryCode");
	if ((lblCountryCode != null)) {
		lblCountryCode.Text = e.Row.DataItem("CountryCode");
	}

	//*** Budget ***'
	Label lblBudget = (Label)e.Row.FindControl("lblBudget");
	if ((lblBudget != null)) {
		lblBudget.Text = Strings.FormatNumber(e.Row.DataItem("Budget"), 2);
	}

	//*** Used ***'
	Label lblUsed = (Label)e.Row.FindControl("lblUsed");
	if ((lblUsed != null)) {
		lblUsed.Text = Strings.FormatNumber(e.Row.DataItem("Used"), 2);
	}

	sumTotal = sumTotal + e.Row.DataItem("Used");

	//*** Total ***'
	Label lblTotal = (Label)e.Row.FindControl("lblTotal");
	if ((lblTotal != null)) {
		lblUsed.Text = Strings.FormatNumber(sumTotal, 2);
	}
}