I'm not sure answer here is correct. There does seem to be a location on schedule C to enter regular bank interest. Section does not seem to differentiate from sole proprietor or other businesses. From IRS Publication 334, Section 7:
"Additions to Gross Profit
If your business has income from a source other than its regular business operations, enter the income on line 6 of Schedule C and add it to gross profit. The result is gross business income. Some examples include income from an interest-bearing checking account, income from scrap sales, income from certain fuel tax credits and refunds, and amounts recovered from bad debts. "
