Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$88.56	7.752%	$95.4252	$95.43	$95.45	$95.40
Purchase #2	$186.96	9.678%	$205.054	$205.05	$205.05	$205.10
Purchase #3	$23.86	8.243%	$25.8268	$25.83	$25.85	$25.80
Purchase #4	$235.31	4.724%	$246.426	$246.43	$246.45	$246.40
Purchase #5	$77.72	9.692%	$85.2526	$85.25	$85.25	$85.30
Purchase #6	$43.94	9.443%	$48.0893	$48.09	$48.10	$48.10
Purchase #7	$238.69	11.396%	$265.8911	$265.89	$265.90	$265.90
7 purchase totals =	$895.04		$971.9650	$971.97	$972.05	$972.00