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	$214.97	11.129%	$238.894	$238.89	$238.90	$238.90
Purchase #2	$105.96	7.266%	$113.6591	$113.66	$113.65	$113.70
Purchase #3	$145.86	6.169%	$154.8581	$154.86	$154.85	$154.90
Purchase #4	$27.90	13.491%	$31.664	$31.66	$31.65	$31.70
Purchase #5	$236.31	6.170%	$250.8903	$250.89	$250.90	$250.90
Purchase #6	$158.52	9.393%	$173.4098	$173.41	$173.40	$173.40
Purchase #7	$132.88	3.718%	$137.8205	$137.82	$137.80	$137.80
7 purchase totals =	$1,022.40		$1,101.1958	$1,101.19	$1,101.15	$1,101.30