Modify cart to determine tax depends on the basket value

gistfile1.php

<?php
// Replace Hook auf engine/core/class/sBasket::getMaxTax
public function getMaxTax(){

  	$sql = "
			SELECT
				SUM(price * quantity) as amount_per_tax, tax
			FROM s_order_basket b
			WHERE b.sessionID=? AND b.modus=0
			GROUP BY tax_rate
			ORDER BY amount_per_tax DESC
		";
		$taxRate = Shopware()->Db()->fetchRow($sql,array(empty(Shopware()->System()->sSESSION_ID) ? session_id() : Shopware()->System()->sSESSION_ID));

		return $taxRate["tax"];
	}