Carrying a small credit card balance from one month to the next will not improve a credit score. You can use a card, have activity reported to the credit bureaus, and build a positive payment history without deliberately leaving debt unpaid.
That distinction matters because a surprisingly persistent piece of credit advice tells people to leave a few dollars on their cards. The theory sounds reasonable at first: Show the scoring system that the card gets used, then prove that you can manage a balance. In reality, the credit card does not need to carry debt across billing cycles to demonstrate responsible use.
