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	$153.58	11.108%	$170.6397	$170.64	$170.65	$170.60
Purchase #2	$167.50	8.210%	$181.2518	$181.25	$181.25	$181.30
Purchase #3	$73.83	12.367%	$82.9606	$82.96	$82.95	$83.00
Purchase #4	$116.74	13.465%	$132.459	$132.46	$132.45	$132.50
Purchase #5	$182.25	5.114%	$191.5703	$191.57	$191.55	$191.60
Purchase #6	$183.49	8.828%	$199.6885	$199.69	$199.70	$199.70
Purchase #7	$123.50	13.692%	$140.4096	$140.41	$140.40	$140.40
7 purchase totals =	$1,000.89		$1,098.9795	$1,098.98	$1,098.95	$1,099.10