I don't really post, just read. But I'd figure I'd chime in as I ship USPS and UPS internationally and domestically almost daily.
It is true that USPS doesn't really offer tracking like UPS and FedEx. However, for domestic shipment they offer Delivery Confirmation that is like tracking lite.
OP, I'm assuming that you are in Canada and getting a shiment from the US since your carrier is Rogers. There should have been a number on the customs form that the shipper should be able to give to you, it's pretty long and ends in US. E.g. LZxxxxxxxxxUS. With that you should be able to track from the USPS website and see when it was handed over to customs, etc. It's not as complete as UPS tracking, but at least it's something. It would not be uncommon that the shipper would not have recorded this number as the Post Office doesnt tell you what it is for.
Also, in my experience, packages can sit a lot longer in Canadian customs that most other countries; don't really know why.
Hope I provided at least some help.