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	$87.62	9.522%	$95.9632	$95.96	$95.95	$96.00
Purchase #2	$222.56	6.634%	$237.3246	$237.32	$237.30	$237.30
Purchase #3	$198.37	8.365%	$214.9637	$214.96	$214.95	$215.00
Purchase #4	$243.67	4.665%	$255.0372	$255.04	$255.05	$255.00
Purchase #5	$42.72	13.846%	$48.635	$48.64	$48.65	$48.60
Purchase #6	$36.96	9.541%	$40.4864	$40.49	$40.50	$40.50
Purchase #7	$242.62	6.418%	$258.1914	$258.19	$258.20	$258.20
7 purchase totals =	$1,074.52		$1,150.6015	$1,150.60	$1,150.60	$1,150.60