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	$191.46	12.269%	$214.9502	$214.95	$214.95	$215.00
Purchase #2	$240.38	5.550%	$253.7211	$253.72	$253.70	$253.70
Purchase #3	$89.50	7.436%	$96.1552	$96.16	$96.15	$96.20
Purchase #4	$183.73	9.185%	$200.6056	$200.61	$200.60	$200.60
Purchase #5	$225.67	5.605%	$238.3188	$238.32	$238.30	$238.30
Purchase #6	$233.87	9.571%	$256.2537	$256.25	$256.25	$256.30
Purchase #7	$225.76	4.255%	$235.3661	$235.37	$235.35	$235.40
7 purchase totals =	$1,390.37		$1,495.3707	$1,495.38	$1,495.30	$1,495.50