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	$61.25	3.737%	$63.5389	$63.54	$63.55	$63.50
Purchase #2	$73.97	13.657%	$84.0721	$84.07	$84.05	$84.10
Purchase #3	$135.48	11.397%	$150.9207	$150.92	$150.90	$150.90
Purchase #4	$235.77	8.429%	$255.6431	$255.64	$255.65	$255.60
Purchase #5	$186.47	4.156%	$194.2197	$194.22	$194.20	$194.20
Purchase #6	$216.60	10.152%	$238.5892	$238.59	$238.60	$238.60
Purchase #7	$185.71	6.667%	$198.0913	$198.09	$198.10	$198.10
7 purchase totals =	$1,095.25		$1,185.0750	$1,185.07	$1,185.05	$1,185.00