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	$175.27	8.585%	$190.3169	$190.32	$190.30	$190.30
Purchase #2	$99.69	11.592%	$111.2461	$111.25	$111.25	$111.20
Purchase #3	$227.67	12.299%	$255.6711	$255.67	$255.65	$255.70
Purchase #4	$142.78	9.103%	$155.7773	$155.78	$155.80	$155.80
Purchase #5	$221.49	6.141%	$235.0917	$235.09	$235.10	$235.10
Purchase #6	$30.85	9.195%	$33.6867	$33.69	$33.70	$33.70
Purchase #7	$60.93	3.122%	$62.8322	$62.83	$62.85	$62.80
7 purchase totals =	$958.68		$1,044.6220	$1,044.63	$1,044.65	$1,044.60