I agree with @leeloo . In most cases, roommate situations do not need to be reported as income. But, in your case ($5000 net income), you probably have a for profit rental.
Q. To reduce net income, then besides square foot, any other divide method can be used legally?
A. Yes. If your roommate has full run of the house, you can use 50% of expenses, including depreciation.
Q. Can I use 50% for expense deduction while using square foot method for depreciation to prevent higher tax bracket issue later after recapture?
A. There's a difference of opinion, in this forum. You'll have to decide or hire a pro.
