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	$190.54	11.177%	$211.8367	$211.84	$211.85	$211.80
Purchase #2	$10.98	3.391%	$11.3523	$11.35	$11.35	$11.40
Purchase #3	$48.52	6.371%	$51.6112	$51.61	$51.60	$51.60
Purchase #4	$158.87	3.399%	$164.27	$164.27	$164.25	$164.30
Purchase #5	$172.70	11.422%	$192.4258	$192.43	$192.45	$192.40
Purchase #6	$199.45	13.227%	$225.8313	$225.83	$225.85	$225.80
Purchase #7	$50.61	5.367%	$53.3262	$53.33	$53.35	$53.30
7 purchase totals =	$831.67		$910.6535	$910.66	$910.70	$910.60