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	$159.85	4.451%	$166.9649	$166.96	$166.95	$167.00
Purchase #2	$38.76	4.189%	$40.3837	$40.38	$40.40	$40.40
Purchase #3	$51.80	4.115%	$53.9316	$53.93	$53.95	$53.90
Purchase #4	$191.28	4.151%	$199.22	$199.22	$199.20	$199.20
Purchase #5	$234.61	13.147%	$265.4542	$265.45	$265.45	$265.50
Purchase #6	$228.96	11.487%	$255.2606	$255.26	$255.25	$255.30
Purchase #7	$182.60	4.367%	$190.5741	$190.57	$190.55	$190.60
7 purchase totals =	$1,087.86		$1,171.7891	$1,171.77	$1,171.75	$1,171.90