I don't understand the point of "uri":"/transactions/1". Isn't the new resource's URI already part of the response (in the Location: header)? It's sort of like saying GET /posts/show/1 vs. GET /posts/1.
It's redundant in that particular instance. But it's a representation of a resource. It might be nice to define the representation across your entire system so that when you grab a transaction resource with a GET later, it still has that URI in it. Or maybe not. But it's not obvious that this is a bad idea.