private void CargarTarjetasDeCredito()
{
this.cboTipoTarjeta.ItemsSource = _ventaBl.ObtenerTarjetasDeCredito();
this.cboTipoTarjeta.DisplayMemberPath = "Nombre";
this.cboTipoTarjeta.SelectedValuePath = "Id";
this.cboTipoTarjeta.SelectedIndex = 0;
}