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	$200.79	11.487%	$223.8547	$223.85	$223.85	$223.90
Purchase #2	$214.29	11.666%	$239.2891	$239.29	$239.30	$239.30
Purchase #3	$48.53	6.197%	$51.5374	$51.54	$51.55	$51.50
Purchase #4	$115.89	13.117%	$131.0913	$131.09	$131.10	$131.10
Purchase #5	$238.61	8.363%	$258.565	$258.57	$258.55	$258.60
Purchase #6	$148.95	13.196%	$168.6054	$168.61	$168.60	$168.60
Purchase #7	$58.62	6.653%	$62.52	$62.52	$62.50	$62.50
7 purchase totals =	$1,025.68		$1,135.4629	$1,135.47	$1,135.45	$1,135.50