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	$213.71	6.198%	$226.9557	$226.96	$226.95	$227.00
Purchase #2	$195.82	13.576%	$222.4045	$222.40	$222.40	$222.40
Purchase #3	$176.66	4.247%	$184.1628	$184.16	$184.15	$184.20
Purchase #4	$100.33	11.227%	$111.594	$111.59	$111.60	$111.60
Purchase #5	$12.87	13.310%	$14.583	$14.58	$14.60	$14.60
Purchase #6	$176.52	3.647%	$182.9577	$182.96	$182.95	$183.00
Purchase #7	$60.52	6.171%	$64.2547	$64.25	$64.25	$64.30
7 purchase totals =	$936.43		$1,006.9124	$1,006.90	$1,006.90	$1,007.10