No penalty for minor breaches: proportional penalties, right to be heard, and voluntary disclosure as mitigating factor. No penalty shall be imposed for minor breaches or easily rectifiable documentation errors made without fraudulent intent or gross negligence; a breach is minor where the tax involved is below the statutory threshold and an error is apparent on the face of the record. Penalties must be proportionate to the facts, imposed only after affording an opportunity to be heard, and must specify the nature of the breach and the applicable provision. Voluntary disclosure before discovery is a mitigating factor. These procedural rules do not apply where the Act prescribes a fixed-sum or fixed-percentage penalty.