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	$190.84	4.495%	$199.4183	$199.42	$199.40	$199.40
Purchase #2	$49.30	13.621%	$56.0152	$56.02	$56.00	$56.00
Purchase #3	$116.82	13.750%	$132.8828	$132.88	$132.90	$132.90
Purchase #4	$151.64	10.643%	$167.779	$167.78	$167.80	$167.80
Purchase #5	$152.71	13.232%	$172.9166	$172.92	$172.90	$172.90
Purchase #6	$195.47	5.121%	$205.48	$205.48	$205.50	$205.50
Purchase #7	$210.83	10.785%	$233.568	$233.57	$233.55	$233.60
7 purchase totals =	$1,067.61		$1,168.0599	$1,168.07	$1,168.05	$1,168.10