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	$211.96	10.607%	$234.4426	$234.44	$234.45	$234.40
Purchase #2	$92.71	4.490%	$96.8727	$96.87	$96.85	$96.90
Purchase #3	$169.65	12.269%	$190.4644	$190.46	$190.45	$190.50
Purchase #4	$245.38	4.677%	$256.8564	$256.86	$256.85	$256.90
Purchase #5	$20.48	11.769%	$22.8903	$22.89	$22.90	$22.90
Purchase #6	$160.61	13.691%	$182.5991	$182.60	$182.60	$182.60
Purchase #7	$55.56	12.733%	$62.6345	$62.63	$62.65	$62.60
7 purchase totals =	$956.35		$1,046.7600	$1,046.75	$1,046.75	$1,046.80