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	$112.59	5.296%	$118.5528	$118.55	$118.55	$118.60
Purchase #2	$215.43	11.660%	$240.5491	$240.55	$240.55	$240.50
Purchase #3	$246.54	7.361%	$264.6878	$264.69	$264.70	$264.70
Purchase #4	$244.94	6.423%	$260.6725	$260.67	$260.65	$260.70
Purchase #5	$26.75	10.628%	$29.593	$29.59	$29.60	$29.60
Purchase #6	$139.46	6.240%	$148.1623	$148.16	$148.15	$148.20
Purchase #7	$79.82	13.837%	$90.8647	$90.86	$90.85	$90.90
7 purchase totals =	$1,065.53		$1,153.0822	$1,153.07	$1,153.05	$1,153.20