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	$92.41	5.267%	$97.2772	$97.28	$97.30	$97.30
Purchase #2	$61.89	5.134%	$65.0674	$65.07	$65.05	$65.10
Purchase #3	$10.77	10.379%	$11.8878	$11.89	$11.90	$11.90
Purchase #4	$77.73	11.530%	$86.6923	$86.69	$86.70	$86.70
Purchase #5	$17.69	13.558%	$20.0884	$20.09	$20.10	$20.10
Purchase #6	$51.72	3.638%	$53.6016	$53.60	$53.60	$53.60
Purchase #7	$210.87	10.307%	$232.6044	$232.60	$232.60	$232.60
7 purchase totals =	$523.08		$567.2191	$567.22	$567.25	$567.30