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	$60.56	3.593%	$62.7359	$62.74	$62.75	$62.70
Purchase #2	$239.64	7.158%	$256.7934	$256.79	$256.80	$256.80
Purchase #3	$240.83	6.146%	$255.6314	$255.63	$255.65	$255.60
Purchase #4	$9.85	9.353%	$10.7713	$10.77	$10.75	$10.80
Purchase #5	$148.26	4.124%	$154.3742	$154.37	$154.35	$154.40
Purchase #6	$37.45	13.253%	$42.4132	$42.41	$42.40	$42.40
Purchase #7	$95.71	3.710%	$99.2608	$99.26	$99.25	$99.30
7 purchase totals =	$832.30		$881.9802	$881.97	$881.95	$882.00