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	$202.39	10.168%	$222.969	$222.97	$222.95	$223.00
Purchase #2	$54.53	12.847%	$61.5355	$61.54	$61.55	$61.50
Purchase #3	$10.89	10.855%	$12.0721	$12.07	$12.05	$12.10
Purchase #4	$14.98	9.478%	$16.3998	$16.40	$16.40	$16.40
Purchase #5	$215.32	5.770%	$227.744	$227.74	$227.75	$227.70
Purchase #6	$165.30	12.267%	$185.5774	$185.58	$185.60	$185.60
Purchase #7	$37.26	3.408%	$38.5298	$38.53	$38.55	$38.50
7 purchase totals =	$700.67		$764.8276	$764.83	$764.85	$764.80