WI sales tax questions?

[mkarps]

I have been just mowing on the side for a while now. I work full time for another company and I do mowing on the side. Should I be collecting sales tax? I have picked up a few more weekly mows this year. I am just doing this a couple nights a week and weekends sometimes. I just filed a DBA and opened business checking so I can have checks made to my business name. I also do a lot of mulching in the spring. I only do around 10k on the side I believe...and yes I did file schedule C last year. If I have to report sales tax can I do at end of tax year? Do I even have to collect it?