They want to be elected again. So they make sure that voters that make a living on exporting goods are feeling good about incoming sales which means they will vote for Harper again.
Then there is more purchase buying from other Countries to Canada because they have an extra 10% profit. Again it benefits businesses.
At the same time we should have never been at par with the USA dollar. It makes no sense, we are not in their same league.
Our economy ain't doing as well as it should, so the loony goes down. Investors buy into countries doing well, which strengthens our money...or the opposite when we're not doing as well as other countries, in this case.