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	$68.46	11.148%	$76.0919	$76.09	$76.10	$76.10
Purchase #2	$56.31	10.646%	$62.3048	$62.30	$62.30	$62.30
Purchase #3	$200.81	11.185%	$223.2706	$223.27	$223.25	$223.30
Purchase #4	$195.94	4.783%	$205.3118	$205.31	$205.30	$205.30
Purchase #5	$212.32	4.399%	$221.66	$221.66	$221.65	$221.70
Purchase #6	$128.49	5.633%	$135.7278	$135.73	$135.75	$135.70
Purchase #7	$89.58	6.631%	$95.52	$95.52	$95.50	$95.50
7 purchase totals =	$951.91		$1,019.8869	$1,019.88	$1,019.85	$1,019.90