Woocommerce Order Quantity in Multiples - woocommerce

Question

I'm trying to restrict woocommerce to only selling in set quantities of 5, 10 or 15.
The code snippet below ( which i found on this forum) allows me to set a minimum quantity of 5 but i'm wondering if anybody could advise if it can be modified to allow 5, 10 or 15.
I appreciate any help you can offer.
add_action( 'woocommerce_checkout_process', 'wc_minimum_order_amount' );
function wc_minimum_order_amount() {
global $woocommerce;
$minimum = 5;
if ( $woocommerce->cart->cart_contents_count < $minimum ) {
$woocommerce->add_error( sprintf( 'Cards can only be purchased in multiples of %s Please ammend your order.' , $minimum ) );
}
}

Answer 1

Thanks to Gareth for his answer, but i actually found a better way of achieving what i need, just posting in case anybody else needs it.
I found it better to restrict the cart to sell in multiples of 5 which can be achieved with the following code.
// check that cart items quantities totals are in multiples of 5
add_action( 'woocommerce_check_cart_items', 'woocommerce_check_cart_quantities' );
function woocommerce_check_cart_quantities() {
global $woocommerce;
$multiples = 5;
$total_products = 0;
foreach ( $woocommerce->cart->get_cart() as $cart_item_key => $values ) {
$total_products += $values['quantity'];
}
if ( ( $total_products % $multiples ) > 0 )
$woocommerce->add_error( sprintf( __('You need to buy in quantities of %s products', 'woocommerce'), $multiples ) );
}

Answer 2

WooCommerce Allow Checkout in Multiples Only, To force the customer to add multiples of a certain quantity to the cart before being able to checkout
<?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' );
}
?>

Answer 3

Not tested but this should work, basically just added the different minimums into an array so the check for $minimum will check all 3 amounts
add_action( 'woocommerce_checkout_process', 'wc_minimum_order_amount' );
function wc_minimum_order_amount() {
global $woocommerce;
$minimum = array('5,'10','15');
if ( $woocommerce->cart->cart_contents_count < $minimum ) {
$woocommerce->add_error( sprintf( 'Cards can only be purchased in multiples of %s Please ammend your order.' , $minimum ) );
}
}

Answer 4

Try using WooCommerce Advanced Product Quantities, it should take care of this for you. Otherwise the below functions are what it uses to get the right step and minimum values for both the cart and product page. Keep in mind that if you only change the input values you'll have to validate them on add to cart and checkout (again the plugin linked below does all of this for you).
http://wordpress.org/plugins/woocommerce-incremental-product-quantities/
Otherwise this filter would probably help for the cart:
add_filter( 'woocommerce_quantity_input_step', 'input_step_value', 1, 2);
function input_step_value( $default, $product ) {
return 5;
}
And this one for the product page:
add_filter( 'woocommerce_quantity_input_args', 'input_set_all_values', 1, 2 );
function input_set_all_values( $args, $product ) {
$args['step'] = 5;
$args['min_value'] = 5;
return $args;
}