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	$144.95	7.289%	$155.5154	$155.52	$155.50	$155.50
Purchase #2	$12.36	13.793%	$14.0648	$14.06	$14.05	$14.10
Purchase #3	$158.58	11.605%	$176.9832	$176.98	$177.00	$177.00
Purchase #4	$59.71	13.701%	$67.8909	$67.89	$67.90	$67.90
Purchase #5	$7.36	6.299%	$7.8236	$7.82	$7.80	$7.80
Purchase #6	$47.83	7.105%	$51.2283	$51.23	$51.25	$51.20
Purchase #7	$127.68	10.524%	$141.117	$141.12	$141.10	$141.10
7 purchase totals =	$558.47		$614.6232	$614.62	$614.60	$614.60