Look up Caddy V2 probably the most dead simple reverse proxy I’ve seen and they have solid documentation

If it’s not an auto-grat why not just raise the prices on the menu 18 percent instead of surprising customers at checkout. Setting prices to cover your business and staff is an important part of running any business. The way they’re doing it is intentianally deceptive. Even down to saying that this is so that they can pay staff instead of just advertising the actual prices in the menu.