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	$114.90	7.770%	$123.8277	$123.83	$123.85	$123.80
Purchase #2	$10.92	4.871%	$11.4519	$11.45	$11.45	$11.50
Purchase #3	$18.32	6.725%	$19.552	$19.55	$19.55	$19.60
Purchase #4	$97.46	13.398%	$110.5177	$110.52	$110.50	$110.50
Purchase #5	$73.25	6.149%	$77.7541	$77.75	$77.75	$77.80
Purchase #6	$48.82	10.154%	$53.7772	$53.78	$53.80	$53.80
Purchase #7	$188.87	8.333%	$204.6085	$204.61	$204.60	$204.60
7 purchase totals =	$552.54		$601.4891	$601.49	$601.50	$601.60