WooCommerce Checkout Add-ons: WPML mult-currency support

wc-checkout-add-ons-wpml-multi-currency.php

function wc_checkout_add_ons_wpml_multi_currency_support( $adjustment ) {

	return apply_filters( 'wcml_raw_price_amount', $adjustment );
}
add_filter( 'woocommerce_checkout_add_on_get_adjustment', 'wc_checkout_add_ons_wpml_multi_currency_support', 100 );
add_filter( 'wc_checkout_add_ons_add_on_option_cost',     'wc_checkout_add_ons_wpml_multi_currency_support', 100 );