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	$133.40	11.437%	$148.657	$148.66	$148.65	$148.70
Purchase #2	$99.92	11.664%	$111.5747	$111.57	$111.55	$111.60
Purchase #3	$205.98	11.341%	$229.3402	$229.34	$229.35	$229.30
Purchase #4	$131.25	13.130%	$148.4831	$148.48	$148.50	$148.50
Purchase #5	$135.60	9.752%	$148.8237	$148.82	$148.80	$148.80
Purchase #6	$180.94	5.439%	$190.7813	$190.78	$190.80	$190.80
Purchase #7	$76.54	11.780%	$85.5564	$85.56	$85.55	$85.60
7 purchase totals =	$963.63		$1,063.2164	$1,063.21	$1,063.20	$1,063.30