Tax and shipping share one shape, a category on the product and the shopper's address, and the unit teaches it once, on the tax page, before covering each. Tax comes first: a provider calculates it, tax zones choose the provider for an address, tax categories map products to the provider's codes, and one setting says whether prices include tax. Shipping follows: every method is a template that reads the fulfilment and creates the rates, worked through with a two-country set-up priced by weight, then the checklist for a method that should appear and does not.
The last page puts both together on a development environment with the mock tax provider, a template method and the mock payment method, so the numbers can be proved before launch. Read the checkout unit's page on addresses and shipping alongside: it covers creating shipping on a checkout and showing the rates.