Is there sales tax per job? How can I determine how much I will need to pay in city/state/federal income taxes at the end of the year?
The income tax you pay will be based upon the net profits of your business. The profit or loss will be taxed on your personal tax return. In addition to income tax, you will be subject to self-employment taxes.
Depending on the amount of tax that you will be have to pay, you may be subject to paying estimated taxes on a quarterly basis during the tax year, rather than just paying 100% of your taxes when you file your income tax return on April 15.
You can almost always call your city and state tax offices, they're generally happy to help educate you and make sure that you proactively comply with any regulations. There's no need for you to try to guess or google the answer when they've got a staff that's ready to to provide the canonical response.