WooCommerce limit checkout to quantities in multiples of a number

gistfile1.php

<?php
// check that cart items quantities totals are in multiples of 6
add_action( 'woocommerce_check_cart_items', 'woocommerce_check_cart_quantities' );
function woocommerce_check_cart_quantities() {
  	$multiples = 6;
	$total_products = 0;
	foreach ( WC()->cart->get_cart() as $cart_item_key => $values ) {
		$total_products += $values['quantity'];
	}
	if ( ( $total_products % $multiples ) > 0 )
		wc_add_notice( sprintf( __('You need to buy in quantities of %s products', 'woocommerce'), $multiples ), 'error' );
}

// Limit cart items with a certain shipping class to be purchased in multiple only
add_action( 'woocommerce_check_cart_items', 'woocommerce_check_cart_quantities_for_class' );
function woocommerce_check_cart_quantities_for_class() {
  	$multiples = 6;
  	$class = 'bottle';
	$total_products = 0;
	foreach ( WC()->cart->get_cart() as $cart_item_key => $values ) {
		$product = get_product( $values['product_id'] );
		if ( $product->get_shipping_class() == $class ) {
			$total_products += $values['quantity'];
		}
	}
	if ( ( $total_products % $multiples ) > 0 )
		wc_add_notice( sprintf( __('You need to purchase bottles in quantities of %s', 'woocommerce'), $multiples ), 'error' );
}
?>

Hi There. I am really struggling with this and wonder if you can help me. i have placed this in the fucntions.php file but it doesn't seem to work in the checkout. It still allows me to check out with 1 product even with this code? Can you help?

Hi. There is no way to set multiplicity for woocommerce attributes? Not only for all products or shipping class. Thank you

please is there a way to set users after purchasing an order, d user cant make another order after a setting period of time

Hi, thanks for your helpful code...

How can I modify it so that it applies to each different shipping class?