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	$56.94	3.719%	$59.0576	$59.06	$59.05	$59.10
Purchase #2	$183.48	4.377%	$191.5109	$191.51	$191.50	$191.50
Purchase #3	$43.26	6.169%	$45.9287	$45.93	$45.95	$45.90
Purchase #4	$217.66	4.406%	$227.2501	$227.25	$227.25	$227.30
Purchase #5	$107.69	3.178%	$111.1124	$111.11	$111.10	$111.10
Purchase #6	$102.76	9.194%	$112.2078	$112.21	$112.20	$112.20
Purchase #7	$189.51	8.401%	$205.4307	$205.43	$205.45	$205.40
7 purchase totals =	$901.30		$952.4982	$952.50	$952.50	$952.50