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	$83.77	13.863%	$95.383	$95.38	$95.40	$95.40
Purchase #2	$62.88	8.287%	$68.0909	$68.09	$68.10	$68.10
Purchase #3	$196.85	12.422%	$221.3027	$221.30	$221.30	$221.30
Purchase #4	$141.40	11.853%	$158.1601	$158.16	$158.15	$158.20
Purchase #5	$243.93	7.765%	$262.8712	$262.87	$262.85	$262.90
Purchase #6	$197.85	12.669%	$222.9156	$222.92	$222.90	$222.90
Purchase #7	$120.27	5.335%	$126.6864	$126.69	$126.70	$126.70
7 purchase totals =	$1,046.95		$1,155.4099	$1,155.41	$1,155.40	$1,155.50