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	$211.92	10.305%	$233.7584	$233.76	$233.75	$233.80
Purchase #2	$16.48	8.579%	$17.8938	$17.89	$17.90	$17.90
Purchase #3	$50.81	9.299%	$55.5348	$55.53	$55.55	$55.50
Purchase #4	$182.86	7.509%	$196.591	$196.59	$196.60	$196.60
Purchase #5	$150.80	11.124%	$167.575	$167.58	$167.60	$167.60
Purchase #6	$135.39	5.222%	$142.4601	$142.46	$142.45	$142.50
Purchase #7	$142.68	13.269%	$161.6122	$161.61	$161.60	$161.60
7 purchase totals =	$890.94		$975.4253	$975.42	$975.45	$975.50