You skip to the else part in after the 4th run of your foreach. Put the $i++
at the end of the loop and your fine.
foreach( $tax_terms as $tax_term ) {
if( $i <= 4 ) {
echo '<td><a href="' . esc_attr( get_term_link( $tax_term, $taxonomy ) ) . '" title="' . sprintf( __( "Profilleri Görüntüle %s" ), $tax_term->name ) . '" ' . '>' . $tax_term->name . '</a></td>';
echo ("\n");
} else {
echo '</tr><tr>';
$i = 0;
}
$i++;
}