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	$58.94	4.588%	$61.6442	$61.64	$61.65	$61.60
Purchase #2	$10.49	6.354%	$11.1565	$11.16	$11.15	$11.20
Purchase #3	$117.56	7.622%	$126.5204	$126.52	$126.50	$126.50
Purchase #4	$78.89	4.128%	$82.1466	$82.15	$82.15	$82.10
Purchase #5	$202.67	5.632%	$214.0844	$214.08	$214.10	$214.10
Purchase #6	$59.98	6.841%	$64.0832	$64.08	$64.10	$64.10
Purchase #7	$249.37	11.648%	$278.4166	$278.42	$278.40	$278.40
7 purchase totals =	$777.90		$838.0519	$838.05	$838.05	$838.00