function mepr_cust_no_vat_to_taxjar( $should_send, $event ) {

  $transaction = $event->get_data();

  if ( strpos( $transaction->tax_desc, __( 'VAT', 'memberpress' ) ) !== false ) {

    $should_send = false;

  }

  return $should_send;

}

add_filter( 'mepr_taxjar_should_send_txn', 'mepr_cust_no_vat_to_taxjar', 10, 2 );