Individuelle Webentwicklung.

// Angebot mit gestaffeltem Mengenrabatt
final class Angebot {
    public function __construct(
        private readonly array $posten,
    ) {}

    public function summe(): float {
        $netto = array_reduce(
            $this->posten,
            fn( $t, $p ) => $t + $p->wert(),
            0.0,
        );
        $faktor = $this->faktor( $netto );
        return round( $netto * $faktor, 2 );
    }

    private function faktor( float $n ): float {
        return 1 - match ( true ) {
            $n >= 10_000 => 0.15,
            $n >=  5_000 => 0.10,
            $n >=  2_000 => 0.05,
            default      => 0.0,
        };
    }
}