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	$236.58	4.585%	$247.4272	$247.43	$247.45	$247.40
Purchase #2	$97.28	3.685%	$100.8648	$100.86	$100.85	$100.90
Purchase #3	$159.70	12.338%	$179.4038	$179.40	$179.40	$179.40
Purchase #4	$153.99	12.725%	$173.5852	$173.59	$173.60	$173.60
Purchase #5	$175.98	6.153%	$186.808	$186.81	$186.80	$186.80
Purchase #6	$144.78	4.762%	$151.6744	$151.67	$151.65	$151.70
Purchase #7	$133.64	6.806%	$142.7355	$142.74	$142.75	$142.70
7 purchase totals =	$1,101.95		$1,182.4989	$1,182.50	$1,182.50	$1,182.50