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	$158.34	8.396%	$171.6342	$171.63	$171.65	$171.60
Purchase #2	$233.49	8.651%	$253.6892	$253.69	$253.70	$253.70
Purchase #3	$200.59	6.231%	$213.0888	$213.09	$213.10	$213.10
Purchase #4	$47.59	12.221%	$53.406	$53.41	$53.40	$53.40
Purchase #5	$105.83	3.439%	$109.4695	$109.47	$109.45	$109.50
Purchase #6	$67.63	6.126%	$71.773	$71.77	$71.75	$71.80
Purchase #7	$153.50	4.575%	$160.5226	$160.52	$160.50	$160.50
7 purchase totals =	$966.97		$1,033.5833	$1,033.58	$1,033.55	$1,033.60