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	$199.89	7.337%	$214.5559	$214.56	$214.55	$214.60
Purchase #2	$73.38	12.665%	$82.6736	$82.67	$82.65	$82.70
Purchase #3	$135.53	5.649%	$143.1861	$143.19	$143.20	$143.20
Purchase #4	$141.85	3.536%	$146.8658	$146.87	$146.85	$146.90
Purchase #5	$156.58	7.603%	$168.4848	$168.48	$168.50	$168.50
Purchase #6	$159.50	9.758%	$175.064	$175.06	$175.05	$175.10
Purchase #7	$213.90	3.363%	$221.0935	$221.09	$221.10	$221.10
7 purchase totals =	$1,080.63		$1,151.9237	$1,151.92	$1,151.90	$1,152.10