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	$69.50	3.673%	$72.0527	$72.05	$72.05	$72.10
Purchase #2	$149.66	13.155%	$169.3478	$169.35	$169.35	$169.30
Purchase #3	$105.64	5.104%	$111.0319	$111.03	$111.05	$111.00
Purchase #4	$12.56	9.584%	$13.7638	$13.76	$13.75	$13.80
Purchase #5	$205.37	4.393%	$214.3919	$214.39	$214.40	$214.40
Purchase #6	$51.34	5.819%	$54.3275	$54.33	$54.35	$54.30
Purchase #7	$85.87	13.230%	$97.2306	$97.23	$97.25	$97.20
7 purchase totals =	$679.94		$732.1462	$732.14	$732.20	$732.10