Schedule C Expenses

As I enter expenses for my rental property, data for Schedule C, Part II; the amount I owe fluctuates as I enter more expenses. For example, if my expenses were $2,000; I may owe $300. When I add more expenses, totaling $5,000; I may owe $400 (not expecting this; shouldn't this be lower). If I add more expenses, the amount owed may decrease (as expected).

 

Shouldn't the taxes owed decrease as I add more expenses?