Necesito ayuda en Visual Basic.Net

[francisco73]

Estoy creando un programa sencillo en Visual Basic.NET que me permita calcular el precio de algunos articulos. Corrí el programa, pero los resultados del precio, sub total del precio (precio del articulo multiplicado por cantidad de articulos) y el tax (4%) me da a $0.00. El problema es que no sé como añadir el código para realizar esto. Soy nuevo en esto, necesito su ayuda...

Código:

Dim Price(100) As Single
    'Para declarar las constantes

        Const Binder_1_Inch_Decimal As Decimal = 1.89
        Const Binder_2_Inches_Decimal As Decimal = 1.99
        Const Calendars_Decimal As Decimal = 8.49
        Const Desktop_Storage_Decimal As Decimal = 4.49
        Const Envelopes_Decimal As Decimal = 1.49
        Const File_Folders_Decimal As Decimal = 2.79
        Const Notebooks_Decimal As Decimal = 1.79
        Const Printer_Cartridge_Decimal As Decimal = 99.99
        Const Scissors_Decimal As Decimal = 1.79
        Const Tape_Decimal As Decimal = 2.99

    Private Function CalcTotal() As Single
        Dim i As Integer
        Dim Binder_1_Inch_Decimal, Binder_2_Inches_Decimal As String
        Dim Total, Tax As Single
        For i = 0 To lstExtPric.Items.Count - 1
            lstExtPric.SetSelected(i, True)
            'Elimina el caracter $ del String
            Binder_1_Inch_Decimal = lstExtPric.SelectedItem.trim("$")
            Total = Total + Val(Binder_1_Inch_Decimal)
        Next
        Tax = Total * 0.05
        txtTotal.Text = FormatCurrency(Total + Tax)

        'Opcional unselecciona lstExtPric
        If lstExtPric.SelectedIndex <> -1 Then
            lstExtPric.SetSelected(lstExtPric.SelectedIndex, False)
        End If

        Return True
    End Function

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        lstChoice.Items.Add("Binder 1 Inch")
        lstChoice.Items.Add("Binder 2 Inches")
        lstChoice.Items.Add("Calendars")
        lstChoice.Items.Add("Desktop Storage")
        lstChoice.Items.Add("Envelopes")
        lstChoice.Items.Add("File Folders")
        lstChoice.Items.Add("Notebooks")
        lstChoice.Items.Add("Printer Cartridge")
        lstChoice.Items.Add("Scissors")
        lstChoice.Items.Add("Tape")

        Dim AllText, LineOfText, A As String
        Dim B() As String
        Dim s As Integer = 0

    End Sub

    Private Sub cmdAdd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdAdd.Click
        Dim Purchase As Integer
        Dim Total As Single
        Purchase = lstChoice.SelectedIndex
        If lstChoice.SelectedIndex <> -1 And Val(txtQty.Text) > 0 Then
            'Añadir la seleccion a la compra
            lstProduct.Items.Add(lstChoice.SelectedItem)
            lstPrice.Items.Add(FormatCurrency(Price(Purchase)))
            lstQty.Items.Add(txtQty.Text)
            lstExtPric.Items.Add(FormatCurrency(Val(txtQty.Text) * Price(Purchase)))
            lstTax.Items.Add(FormatCurrency(Val(txtQty.Text) * Price(Purchase) * 0.04))
            Call CalcTotal()
        Else
            MsgBox("Select Item from List!" & vbCrLf & "Quantity must be greater than 0.", MsgBoxStyle.Critical, "Error")
        End If

    End Sub

    Private Sub cmdReset_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdReset.Click
        lstProduct.Items.Clear()
        lstQty.Items.Clear()
        lstPrice.Items.Clear()
        lstExtPric.Items.Clear()
        lstTax.Items.Clear()
        txtTotal.Text = ""
    End Sub

    Private Sub cmdRemove_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdRemove.Click
        Dim s As Integer = lstProduct.SelectedIndex
        If lstProduct.SelectedIndex <> -1 Then
            lstProduct.Items.RemoveAt(s)
            lstQty.Items.RemoveAt(s)
            lstPrice.Items.RemoveAt(s)
            lstExtPric.Items.RemoveAt(s)
            lstTax.Items.RemoveAt(s)
            Call CalcTotal()
        Else
            MsgBox("Select Item from Product List!", MsgBoxStyle.Critical, "Error")
        End If
    End Sub

    Private Sub cmdExit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdExit.Click
        End
    End Sub
End Class