The HST for Ontario is calculated from Ontario rate (8%) and Canada rate (5%) for a total of 13%. This rate is the same since July 1st 2010.
No change on the HST rate as been made for Ontario in 2021.
Amount with sales tax / (1+ (HST rate/100)) = Amount without sales tax
Amount without sales tax x (HST rate/100) = Amount of HST in Ontario
100$ / (1+(13/100)) = 88.50$ (88,495575$)
88,495575$ x (13/100) = 11.50$
Note: The amount without sales tax of Ontario in this situation should not be rounded before the HST is calculated.