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	$117.49	8.488%	$127.4626	$127.46	$127.45	$127.50
Purchase #2	$13.86	10.776%	$15.3536	$15.35	$15.35	$15.40
Purchase #3	$186.50	5.519%	$196.7929	$196.79	$196.80	$196.80
Purchase #4	$235.26	10.186%	$259.2236	$259.22	$259.20	$259.20
Purchase #5	$107.25	11.370%	$119.4443	$119.44	$119.45	$119.40
Purchase #6	$220.94	3.167%	$227.9372	$227.94	$227.95	$227.90
Purchase #7	$197.42	12.272%	$221.6474	$221.65	$221.65	$221.60
7 purchase totals =	$1,078.72		$1,167.8616	$1,167.85	$1,167.85	$1,167.80