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	$161.71	4.772%	$169.4268	$169.43	$169.45	$169.40
Purchase #2	$38.64	12.792%	$43.5828	$43.58	$43.60	$43.60
Purchase #3	$70.54	10.724%	$78.1047	$78.10	$78.10	$78.10
Purchase #4	$49.31	6.527%	$52.5285	$52.53	$52.55	$52.50
Purchase #5	$146.41	6.305%	$155.6412	$155.64	$155.65	$155.60
Purchase #6	$112.95	3.118%	$116.4718	$116.47	$116.45	$116.50
Purchase #7	$157.87	12.873%	$178.1926	$178.19	$178.20	$178.20
7 purchase totals =	$737.43		$793.9484	$793.94	$794.00	$793.90