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	$151.50	4.310%	$158.0297	$158.03	$158.05	$158.00
Purchase #2	$233.47	9.231%	$255.0216	$255.02	$255.00	$255.00
Purchase #3	$65.77	7.502%	$70.7041	$70.70	$70.70	$70.70
Purchase #4	$171.80	4.401%	$179.3609	$179.36	$179.35	$179.40
Purchase #5	$197.73	5.437%	$208.4806	$208.48	$208.50	$208.50
Purchase #6	$193.72	10.245%	$213.5666	$213.57	$213.55	$213.60
Purchase #7	$55.64	10.437%	$61.4471	$61.45	$61.45	$61.40
7 purchase totals =	$1,069.63		$1,146.6106	$1,146.61	$1,146.60	$1,146.60