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	$106.64	11.556%	$118.9633	$118.96	$118.95	$119.00
Purchase #2	$184.98	6.113%	$196.2878	$196.29	$196.30	$196.30
Purchase #3	$205.59	10.256%	$226.6753	$226.68	$226.70	$226.70
Purchase #4	$20.92	7.518%	$22.4928	$22.49	$22.50	$22.50
Purchase #5	$166.47	11.497%	$185.6091	$185.61	$185.60	$185.60
Purchase #6	$10.69	10.625%	$11.8258	$11.83	$11.85	$11.80
Purchase #7	$165.34	11.726%	$184.7278	$184.73	$184.75	$184.70
7 purchase totals =	$860.63		$946.5819	$946.59	$946.65	$946.60