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	$190.47	13.243%	$215.6939	$215.69	$215.70	$215.70
Purchase #2	$10.46	4.276%	$10.9073	$10.91	$10.90	$10.90
Purchase #3	$40.43	13.543%	$45.9054	$45.91	$45.90	$45.90
Purchase #4	$90.58	5.488%	$95.551	$95.55	$95.55	$95.60
Purchase #5	$200.47	7.425%	$215.3549	$215.35	$215.35	$215.40
Purchase #6	$105.45	4.414%	$110.1046	$110.10	$110.10	$110.10
Purchase #7	$50.76	6.853%	$54.2386	$54.24	$54.25	$54.20
7 purchase totals =	$688.62		$747.7557	$747.75	$747.75	$747.80