The main table salt seller in Canada lists sugar in their ingredients for ordinary table salt. In ordinary iodized table salt, you expect to see potassium iodide, as well as an anti-caking agent (calcium silicate). But sugar? I e-mailed the company to inquire about this, but got no reply. I wasn't particularly surprised not to get a reply, as I doubt there is a good reason for adding sugar to salt.
Chowhounds around the world who use ordinary table salt, check your box at home. Does it contain sugar?