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	$199.42	11.123%	$221.6015	$221.60	$221.60	$221.60
Purchase #2	$227.43	12.200%	$255.1765	$255.18	$255.20	$255.20
Purchase #3	$154.92	4.478%	$161.8573	$161.86	$161.85	$161.90
Purchase #4	$41.83	8.223%	$45.2697	$45.27	$45.25	$45.30
Purchase #5	$133.50	8.141%	$144.3682	$144.37	$144.35	$144.40
Purchase #6	$84.63	8.115%	$91.4977	$91.50	$91.50	$91.50
Purchase #7	$139.65	3.662%	$144.764	$144.76	$144.75	$144.80
7 purchase totals =	$981.38		$1,064.5349	$1,064.54	$1,064.50	$1,064.70