We shipped a change a few months ago to waive invoices under $5. We haven’t had any reason to disable it yet, it seems to be useful. A surprising number of people pay <$5 by accident and charging them creates a negative experience. And, the reality is we make money off bigger spenders.
We’re actually considering ditching the free tier altogether and just making this the free tier. I think it sets a good expectation (these services are worth money, we’re electing not to charge you, but it’s definitely valuable).