Kudos to you, that's awesome, especially giving most of it to charity. How did you reach your customers? At 5 dollars per sale, that's around 100 customers per month for something that seems relatively non-essential
Google analytics shows traffic as mostly direct and from Google; the next largest fraction coming from Reddit (I shared it a few times), and many from GitHub. I have never paid for advertisements.
The first time I shared it on HN it went to the front page :)
