In Canada, gas prices are listed per litre instead of per gallon. According to Google, 1 US gallon = 3.7854118 litres. We have a lot of taxes on our gas, so the prices are always higher than in the US.
Anyway, if you are looking to find out what the price of gas is, then the best place to look at OntarioGasPrices.com. This is part of the much larger GasBuddy.com chain of sites. According to the Niagara Falls page, the price of gas ranges from 109.3¢/L to 109.9¢/L. The price of gas in Niagara Falls is almost always a few cents more per litre than surrounding areas. Prices in St. Catharines currently range from 102.3¢/L to 103.9¢/L.