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	$94.99	5.130%	$99.863	$99.86	$99.85	$99.90
Purchase #2	$145.59	8.795%	$158.3946	$158.39	$158.40	$158.40
Purchase #3	$77.70	12.848%	$87.6829	$87.68	$87.70	$87.70
Purchase #4	$208.54	8.733%	$226.7518	$226.75	$226.75	$226.80
Purchase #5	$200.29	7.359%	$215.0293	$215.03	$215.05	$215.00
Purchase #6	$90.54	9.476%	$99.1196	$99.12	$99.10	$99.10
Purchase #7	$118.75	7.473%	$127.6242	$127.62	$127.60	$127.60
7 purchase totals =	$936.40		$1,014.4654	$1,014.45	$1,014.45	$1,014.50