Conversion tracking requires type, event, qty (quantity), sku, and price. This enables our clients to measure the incremental lift in conversions that Syndigo produces.
window.SYNDI = window.SYNDI || [];
window.SYNDI.push({
     "type": "track",
     "event": "transaction",
     "orderid": "12341234ASDF",
     "total": "1201.456",
     "items": [
         {
             "sku": "1234123r4",
             "price": "123.546",
             "count": "123"
         },
         {
             "sku": "12asdfa4123r4",
             "price": "12.546",
             "count": "1",
             "customParam1": "foo"
         }
     ],
     "customParam2": "bar"
});