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	$65.33	9.385%	$71.4612	$71.46	$71.45	$71.50
Purchase #2	$195.90	13.355%	$222.0624	$222.06	$222.05	$222.10
Purchase #3	$41.39	5.295%	$43.5816	$43.58	$43.60	$43.60
Purchase #4	$10.29	10.507%	$11.3712	$11.37	$11.35	$11.40
Purchase #5	$211.93	8.560%	$230.0712	$230.07	$230.05	$230.10
Purchase #6	$236.77	10.726%	$262.166	$262.17	$262.15	$262.20
Purchase #7	$229.91	6.626%	$245.1438	$245.14	$245.15	$245.10
7 purchase totals =	$991.52		$1,085.8574	$1,085.85	$1,085.80	$1,086.00