Correct
A continuation allows asynchronous processing for long-running requests, meaning each callout can take its time without blocking the Visualforce page.

By using Continuations for both callouts, the developer can ensure that each callout will wait for completion without a risk of timeout. Since the billing callout response is needed for the tax callout, the Continuation framework supports chaining, so you can process the billing response and use it in the tax callout.