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	$59.37	5.316%	$62.5261	$62.53	$62.55	$62.50
Purchase #2	$9.83	4.531%	$10.2754	$10.28	$10.30	$10.30
Purchase #3	$162.37	4.487%	$169.6555	$169.66	$169.65	$169.70
Purchase #4	$158.65	10.324%	$175.029	$175.03	$175.05	$175.00
Purchase #5	$220.89	7.756%	$238.0222	$238.02	$238.00	$238.00
Purchase #6	$114.80	7.600%	$123.5248	$123.52	$123.50	$123.50
Purchase #7	$19.37	12.404%	$21.7727	$21.77	$21.75	$21.80
7 purchase totals =	$745.28		$800.8057	$800.81	$800.80	$800.80