private void ShowTotalPriceRaw()
{
currentCylinder.ComputePricePerPiece();
currentCylinder.ComputeTotalPrice();
TxtPricePerPiece.Text = string.Format("{0:C2}", ((Cylinder)comboBox1.SelectedItem).Price_Per_Piece);
TxtTotalRaw.Text = string.Format("{0:C2}", ((Cylinder)comboBox1.SelectedItem).Total);
}