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	$180.55	10.258%	$199.0708	$199.07	$199.05	$199.10
Purchase #2	$195.31	10.419%	$215.6593	$215.66	$215.65	$215.70
Purchase #3	$6.42	6.509%	$6.8379	$6.84	$6.85	$6.80
Purchase #4	$203.99	7.423%	$219.1322	$219.13	$219.15	$219.10
Purchase #5	$115.84	13.287%	$131.2317	$131.23	$131.25	$131.20
Purchase #6	$10.45	4.650%	$10.9359	$10.94	$10.95	$10.90
Purchase #7	$213.33	4.507%	$222.9448	$222.94	$222.95	$222.90
7 purchase totals =	$925.89		$1,005.8126	$1,005.81	$1,005.85	$1,005.70