Set product price by quantity and discount

/**
 * get percentage by quantity
 */
function sakib_get_discount( $quantity ) {
    switch ($quantity) {
        case 6:
            $discount = 20;
            break;
        case 10:
            $discount = 30;
            break;
        default:
            $discount = 0;
    }
    return $discount / 100;
}

/**
 * Set dynamic product price or discount by quantity
 * 
 * @param $cart_object
 * 
 * @return void
 */
function sakib__cart_item_price( $cart_object ){

    if ( is_admin() && ! defined( 'DOING_AJAX' ) )
        return;

    // Required since Woocommerce version 3.2 for cart items properties changes
    if ( did_action( 'woocommerce_before_calculate_totals' ) >= 2 )
        return;

    foreach ( $cart_object->get_cart() as $cart_item ) {
        // discounts by quantity
        $new_price = $cart_item['data']->get_regular_price() - ( $cart_item['data']->get_regular_price() * sakib_get_discount( (int) $cart_item['quantity'] ) );
        $cart_item['data']->set_price( $new_price );
        
    }
}

add_action( 'woocommerce_before_calculate_totals', 'sakib__cart_item_price', 20, 1 );