I found this information from the IRS (https://www.irs.gov/instructions/i1099int/ar02.html#d0e223). According to the Box1 section for interest income, it seems like if my bank account interests is less than $10, then I don't need to report it on my 2015 tax return (form 1040). Please correct me if my understanding is incorrect.
In addition, since I did not get a 1099-INT, what should I put for these boxes?
Your understanding is incorrect. If the amount is under $10, then the payer is not required to send you a 1099-INT, however, you are required to report all income whether you get a 1099-INT or not. Any income that is more than 49 cents is reportable and taxable.
You enter the interest as if you had received a 1099-int, just put the bank name as the payer and put the interest in Box 1. That is all you have to do.
Do I need to put account numbers and routing number when I file my interest on bank account