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	$169.93	13.385%	$192.6751	$192.68	$192.70	$192.70
Purchase #2	$158.27	8.733%	$172.0917	$172.09	$172.10	$172.10
Purchase #3	$82.81	3.747%	$85.9129	$85.91	$85.90	$85.90
Purchase #4	$245.63	11.635%	$274.2091	$274.21	$274.20	$274.20
Purchase #5	$54.89	9.210%	$59.9454	$59.95	$59.95	$59.90
Purchase #6	$52.62	11.221%	$58.5245	$58.52	$58.50	$58.50
Purchase #7	$170.41	3.332%	$176.0881	$176.09	$176.10	$176.10
7 purchase totals =	$934.56		$1,019.4468	$1,019.45	$1,019.45	$1,019.40