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	$210.28	7.733%	$226.541	$226.54	$226.55	$226.50
Purchase #2	$67.66	5.372%	$71.2947	$71.29	$71.30	$71.30
Purchase #3	$223.34	9.756%	$245.1291	$245.13	$245.15	$245.10
Purchase #4	$223.35	7.864%	$240.9142	$240.91	$240.90	$240.90
Purchase #5	$135.63	11.252%	$150.8911	$150.89	$150.90	$150.90
Purchase #6	$227.73	12.191%	$255.4926	$255.49	$255.50	$255.50
Purchase #7	$52.85	6.845%	$56.4676	$56.47	$56.45	$56.50
7 purchase totals =	$1,140.84		$1,246.7303	$1,246.72	$1,246.75	$1,246.70