Canada is a perfect example of the problem you are describing. There is no single Canada rate to look up. Ontario charges 13 percent HST, Alberta charges 5 percent GST only, and BC splits it into 5 percent GST plus 7 percent PST. Quebec is where most hand rolled logic quietly breaks, because QST is calculated on the pre GST price, so a $100 sale comes to $114.98, and any code that just applies rates one after another on a running total gets it wrong. Then product category changes the answer again, in Manitoba groceries are taxed differently from general merchandise. Maintaining a research database across all of that goes stale fast, which is exactly why we built TrueNorth API. One call covers all 13 provinces and territories across 41 product categories, so a pipeline like this one can ask for the correct total instead of maintaining the rules itself.