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	$75.42	13.843%	$85.8604	$85.86	$85.85	$85.90
Purchase #2	$78.58	12.424%	$88.3428	$88.34	$88.35	$88.30
Purchase #3	$117.60	5.352%	$123.894	$123.89	$123.90	$123.90
Purchase #4	$193.80	11.687%	$216.4494	$216.45	$216.45	$216.40
Purchase #5	$66.94	11.430%	$74.5912	$74.59	$74.60	$74.60
Purchase #6	$227.87	13.377%	$258.3522	$258.35	$258.35	$258.40
Purchase #7	$107.35	3.508%	$111.1158	$111.12	$111.10	$111.10
7 purchase totals =	$867.56		$958.6058	$958.60	$958.60	$958.60