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	$149.65	4.288%	$156.067	$156.07	$156.05	$156.10
Purchase #2	$15.26	3.749%	$15.8321	$15.83	$15.85	$15.80
Purchase #3	$171.60	4.643%	$179.5674	$179.57	$179.55	$179.60
Purchase #4	$148.49	13.643%	$168.7485	$168.75	$168.75	$168.70
Purchase #5	$146.66	4.767%	$153.6513	$153.65	$153.65	$153.70
Purchase #6	$194.87	13.740%	$221.6451	$221.65	$221.65	$221.60
Purchase #7	$164.90	12.496%	$185.5059	$185.51	$185.50	$185.50
7 purchase totals =	$991.43		$1,081.0173	$1,081.03	$1,081.00	$1,081.00