When any dealer fails to make any return or to pay the full amount of the tax required by this article, there shall be imposed, in addition to other penalties provided by law, a penalty to be added to the tax in the amount of 5 percent or $5.00, whichever is greater, if the failure is for not more than 30 days and an additional 5 percent or $5.00, whichever is greater, for each additional 30 days or fraction of 30 days during which the failure continues. The penalty for any single violation shall not exceed 25 percent or $25.00 in the aggregate, whichever is greater. If the failure is due to providential cause shown to the satisfaction of the commissioner in affidavit form attached to the return and remittance is made within ten days of due date, the return may be accepted exclusive of penalties and interest. In the case of a false or fraudulent return or of a failure to file a return where willful intent exists to defraud the state of any tax due under this article, a penalty of 50 percent of the tax due shall be assessed.