google-analytics-modify-transaction.js

$.ajax({
    type: "POST",
    url: 'https://ssl.google-analytics.com/collect',
    async: false,
    data: {
        v: "1",
        tid: "UA-XXXXXXX-XX",
        cid: "Unique Client ID",
        t: "transaction",
        ti: "transaction ID",
        tr: "+ / - revenue value",
        tt: "+ / - tax value",
        ts: "+ / - shipping value",
        cu: "currency code"
    }
});