Good breakdown. In Canada this choice gets complicated because the rate itself changes by province, so tax exclusive display has to be dynamic. A $100 item shows $105 in Alberta, $113 in Ontario with 13 percent HST, and $114.98 in Quebec with 5 percent GST plus 9.975 percent QST calculated on the pre GST price. Tax inclusive pricing hides that complexity, but you still have to back the tax out correctly per province for remittance. TrueNorth API has a calculate tax endpoint that returns the full breakdown per province, which makes either display mode a rendering decision instead of a math problem.