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	$244.89	3.682%	$253.9068	$253.91	$253.90	$253.90
Purchase #2	$179.85	3.229%	$185.6574	$185.66	$185.65	$185.70
Purchase #3	$71.42	7.622%	$76.8636	$76.86	$76.85	$76.90
Purchase #4	$195.48	4.733%	$204.7321	$204.73	$204.75	$204.70
Purchase #5	$75.81	10.496%	$83.767	$83.77	$83.75	$83.80
Purchase #6	$63.32	10.785%	$70.1491	$70.15	$70.15	$70.10
Purchase #7	$162.32	3.694%	$168.3161	$168.32	$168.30	$168.30
7 purchase totals =	$993.09		$1,043.3921	$1,043.40	$1,043.35	$1,043.40