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	$38.88	10.771%	$43.0678	$43.07	$43.05	$43.10
Purchase #2	$247.53	9.715%	$271.5775	$271.58	$271.60	$271.60
Purchase #3	$103.93	8.413%	$112.6736	$112.67	$112.65	$112.70
Purchase #4	$151.74	5.558%	$160.1737	$160.17	$160.15	$160.20
Purchase #5	$187.59	9.568%	$205.5386	$205.54	$205.55	$205.50
Purchase #6	$211.99	5.245%	$223.1089	$223.11	$223.10	$223.10
Purchase #7	$104.83	6.336%	$111.472	$111.47	$111.45	$111.50
7 purchase totals =	$1,046.49		$1,127.6121	$1,127.61	$1,127.55	$1,127.70