Rule source on GitHub

DowngradeRoundingModeEnumRector

Replace RoundingMode enum to rounding mode constant in round()

-round(1.5, 0, RoundingMode::HalfAwayFromZero);
+round(1.5, 0, PHP_ROUND_HALF_UP);

Configure your rector.php:

<?php

use Rector\Config\RectorConfig;
use Rector\DowngradePhp84\Rector\FuncCall\DowngradeRoundingModeEnumRector;

return RectorConfig::configure()
    ->withRules([
        DowngradeRoundingModeEnumRector::class,
    ]);