1.Usage of present simple tense: The answer uses the present simple tense ("I always carry", "they come in handy", "they're also useful") to describe habitual actions, which is appropriate for the context.
2.Parallel structure: The answer uses parallel structure effectively in the list of uses for coins ("for small purchases like snacks or bus fare, and they're also useful for vending machines and parking meters"), making the sentence clear and easy to follow.