keep running total and change to currency

Can you  help me figure out how to keep an accurate running total when using the wizard control, and convert these results to a currency value? (because I'm going to have send this value as payment to paypal, so I need currency instead of string--and, of course, accurate) Thanks.

Protected Sub Wizard1_ActiveStepChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles Wizard1.ActiveStepChanged
        Select Case Wizard1.ActiveStepIndex
            Case 0
                'How many users                
            Case 1
                lblTally.Text = 23 + rdoConcurrentUsers.SelectedValue
            Case 2
                lblTally.Text = 23 + rdoConcurrentUsers.SelectedValue * rdoHours.SelectedValue
            Case 3
                lblReport.ForeColor = Drawing.Color.Red
                lblReport.Text = "This is a summary of your selections for a webcast service commencing on " & _
                RadDateTimePicker1.SelectedDate & ", for " & rdoHours.SelectedItem.Text & " hours, to support up to " & _
                rdoConcurrentUsers.SelectedItem.Text & " total users." & " If this is correct, click Finish to checkout."
        End Select
    End Sub
 
    Protected Sub rdoConcurrentUsers_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs)
        lblTxtTotal.Visible = True
        lblTally.Text = 23 + rdoConcurrentUsers.SelectedValue
    End Sub
 
    Protected Sub rdoHours_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs)
        lblTally.Text = 23 + rdoConcurrentUsers.SelectedValue * rdoHours.SelectedValue
    End Sub

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