The HST is short for the Harmonized Sales Tax and it is a Provincial Tax. 

A listing has been  prepared by the Provincial Government.  It outlines what the GST was on products prior to July 1st, 2010, as well as, outlining what the applicable RST was for the same time frame.  It also shows if there has been a change to the combined tax as a result of harmonization.  This listing has been segmented very methodically by Category and makes it fairly easy to understand.

If you are interested in looking at the detailed commodity listing  Click Here.