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	$209.87	12.180%	$235.4322	$235.43	$235.45	$235.40
Purchase #2	$185.53	4.707%	$194.2629	$194.26	$194.25	$194.30
Purchase #3	$146.26	10.496%	$161.6114	$161.61	$161.60	$161.60
Purchase #4	$175.57	9.121%	$191.5837	$191.58	$191.60	$191.60
Purchase #5	$131.75	9.750%	$144.5956	$144.60	$144.60	$144.60
Purchase #6	$107.95	3.220%	$111.426	$111.43	$111.45	$111.40
Purchase #7	$106.39	7.147%	$113.9937	$113.99	$114.00	$114.00
7 purchase totals =	$1,063.32		$1,152.9055	$1,152.90	$1,152.95	$1,152.90