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	$174.67	12.722%	$196.8915	$196.89	$196.90	$196.90
Purchase #2	$13.40	4.286%	$13.9743	$13.97	$13.95	$14.00
Purchase #3	$121.46	12.136%	$136.2004	$136.20	$136.20	$136.20
Purchase #4	$119.79	3.232%	$123.6616	$123.66	$123.65	$123.70
Purchase #5	$151.90	13.678%	$172.6769	$172.68	$172.70	$172.70
Purchase #6	$214.40	11.130%	$238.2627	$238.26	$238.25	$238.30
Purchase #7	$77.54	12.323%	$87.0953	$87.10	$87.10	$87.10
7 purchase totals =	$873.16		$968.7627	$968.76	$968.75	$968.90