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	$174.83	11.557%	$195.0351	$195.04	$195.05	$195.00
Purchase #2	$38.93	3.796%	$40.4078	$40.41	$40.40	$40.40
Purchase #3	$176.34	11.515%	$196.6456	$196.65	$196.65	$196.60
Purchase #4	$69.37	11.606%	$77.4211	$77.42	$77.40	$77.40
Purchase #5	$50.84	4.422%	$53.0881	$53.09	$53.10	$53.10
Purchase #6	$152.34	6.368%	$162.041	$162.04	$162.05	$162.00
Purchase #7	$12.49	7.688%	$13.4502	$13.45	$13.45	$13.50
7 purchase totals =	$675.14		$738.0889	$738.10	$738.10	$738.00