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	$233.76	5.169%	$245.8431	$245.84	$245.85	$245.80
Purchase #2	$144.70	6.398%	$153.9579	$153.96	$153.95	$154.00
Purchase #3	$129.99	11.419%	$144.8336	$144.83	$144.85	$144.80
Purchase #4	$48.84	4.381%	$50.9797	$50.98	$51.00	$51.00
Purchase #5	$39.77	4.410%	$41.5239	$41.52	$41.50	$41.50
Purchase #6	$156.95	6.728%	$167.5096	$167.51	$167.50	$167.50
Purchase #7	$142.81	4.203%	$148.8123	$148.81	$148.80	$148.80
7 purchase totals =	$896.82		$953.4601	$953.45	$953.45	$953.40