Magento如何按购买的产品数量来算折扣?

一种方法是设置Tier Price分层价格,适用于少量产品,可直接在产品编辑=>Prices选项卡下的Tier Price设置(如下图所示);

阿里云-推广AD

另一种方法是设置定价规则(可全局批量应用),你可参考下面几篇文章:
http://www.4u4v.net/magentos-pricing-rules-for-information.html
http://www.4u4v.net/how-to-set-the-conditions-for-magento-pricing-rules.html
http://www.4u4v.net/how-to-set-pricing-rules-for-action-magento.html
http://www.4u4v.net/magentos-a-different-price-rules-shopping-cart-price-rules.html