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	$59.37	3.814%	$61.6344	$61.63	$61.65	$61.60
Purchase #2	$103.58	13.416%	$117.4763	$117.48	$117.50	$117.50
Purchase #3	$108.93	10.657%	$120.5387	$120.54	$120.55	$120.50
Purchase #4	$209.65	4.349%	$218.7677	$218.77	$218.75	$218.80
Purchase #5	$211.98	4.297%	$221.0888	$221.09	$221.10	$221.10
Purchase #6	$59.88	5.863%	$63.3908	$63.39	$63.40	$63.40
Purchase #7	$230.48	12.307%	$258.8452	$258.85	$258.85	$258.80
7 purchase totals =	$983.87		$1,061.7419	$1,061.75	$1,061.80	$1,061.70