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	$176.96	11.273%	$196.9087	$196.91	$196.90	$196.90
Purchase #2	$146.35	3.491%	$151.4591	$151.46	$151.45	$151.50
Purchase #3	$223.60	8.274%	$242.1007	$242.10	$242.10	$242.10
Purchase #4	$9.28	7.261%	$9.9538	$9.95	$9.95	$10.00
Purchase #5	$136.38	11.113%	$151.5359	$151.54	$151.55	$151.50
Purchase #6	$185.83	4.447%	$194.0939	$194.09	$194.10	$194.10
Purchase #7	$100.65	7.636%	$108.3356	$108.34	$108.35	$108.30
7 purchase totals =	$979.05		$1,054.3877	$1,054.39	$1,054.40	$1,054.40