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	$85.83	11.647%	$95.8266	$95.83	$95.85	$95.80
Purchase #2	$200.26	11.827%	$223.9448	$223.94	$223.95	$223.90
Purchase #3	$94.75	6.218%	$100.6416	$100.64	$100.65	$100.60
Purchase #4	$47.50	13.632%	$53.9752	$53.98	$54.00	$54.00
Purchase #5	$136.53	11.816%	$152.6624	$152.66	$152.65	$152.70
Purchase #6	$158.30	9.738%	$173.7153	$173.72	$173.70	$173.70
Purchase #7	$56.28	9.557%	$61.6587	$61.66	$61.65	$61.70
7 purchase totals =	$779.45		$862.4246	$862.43	$862.45	$862.40