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	$116.68	12.214%	$130.9313	$130.93	$130.95	$130.90
Purchase #2	$50.68	13.792%	$57.6698	$57.67	$57.65	$57.70
Purchase #3	$146.47	13.855%	$166.7634	$166.76	$166.75	$166.80
Purchase #4	$207.37	4.443%	$216.5834	$216.58	$216.60	$216.60
Purchase #5	$155.79	4.347%	$162.5622	$162.56	$162.55	$162.60
Purchase #6	$63.64	13.737%	$72.3822	$72.38	$72.40	$72.40
Purchase #7	$241.95	5.341%	$254.8725	$254.87	$254.85	$254.90
7 purchase totals =	$982.58		$1,061.7648	$1,061.75	$1,061.75	$1,061.90