Visa Application Help- What counts as a penalty?

[smilefreak16]

Hello,

Hope someone may be able to provide some guidance in regards to this query. Currently applying for visa (spouse route), and have noticed the question on penalties and warnings. I initially thought this did not apply to our application. However, as a US citizen I have paid penalty payments for failure to file and pay taxes on time for 2015 tax year. Upon receiving the penalty notice (December 2016), I made sure to pay immediately. The penalty was not huge (less than $50). As such, I am concerned if this should be included on the application. I want to ensure we are completing the application perfectly. Also, in regards to this matter, would this be considered grounds for refusal?

Thanks for any advice given!