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	$216.72	5.500%	$228.6396	$228.64	$228.65	$228.60
Purchase #2	$81.34	5.401%	$85.7332	$85.73	$85.75	$85.70
Purchase #3	$28.83	11.120%	$32.0359	$32.04	$32.05	$32.00
Purchase #4	$20.40	3.108%	$21.034	$21.03	$21.05	$21.00
Purchase #5	$14.29	3.192%	$14.7461	$14.75	$14.75	$14.70
Purchase #6	$180.93	9.662%	$198.4115	$198.41	$198.40	$198.40
Purchase #7	$138.72	9.266%	$151.5738	$151.57	$151.55	$151.60
7 purchase totals =	$681.23		$732.1741	$732.17	$732.20	$732.00