Your percentages are exactly in line with the average software sales. So it sounds like you need to increase the traffic to your site.
Advertising is unlikely to pay off, because bringing the 50-100 people needed to make one sale is bound to cost more than $9 you'll earn from that sales.
Based on the kind of software it is, I would try to reach out to various bloggers that discuss windows productivity and beginner tools. One starts mentioning it, then another, and over time you build your traffic up. But it will take time.
You should prefer some online marketing consultancy. There are many tactics available for online marketing and advertising. Google Adwords is the best tool to increase traffic and improve conversation, but it is necessary that you need to do some analysis to reduce the cost per conversation like keyword matching, user locations, conversation time and many more. At the current time, Content marketing and social media is the most effective techniques for online marketing. You can contact or hire some professional bloggers for content marketing. Infographic and video marketing can help you to enhance brand reputation. There are many more ways to promote your business online.