order tiers

functions.php

<?php
add_filter('gens_raf_coupon_amount','change_coupon_amount',10, 2);
function change_coupon_amount($amount,$order_id){
    // get number of referrals
    $referrer_id = get_post_meta($order_id,'_wpgens_raf_id',true);
    $user = reset(get_users(array('meta_key' => 'gens_referral_id', 'meta_value' => $referrer_id)));
    $customer_orders = get_posts( array(
        'numberposts' => - 1,
        'meta_key'    => '_customer_user',
        'meta_value'  => $user->ID,
        'post_type'   => array( 'shop_order' ),
        'post_status' => array( 'wc-completed' )
    ) );

    $total = 0;
    foreach ( $customer_orders as $customer_order ) {
        $order = wc_get_order( $customer_order );
        $total += $order->get_total();
    }
    
    if($total > 500){
		return $amount * 5;
    } else if($total > 1000){
		return $amount * 10;
    }
    return $amount;
}