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	$41.92	9.829%	$46.0403	$46.04	$46.05	$46.00
Purchase #2	$73.56	6.733%	$78.5128	$78.51	$78.50	$78.50
Purchase #3	$195.39	10.198%	$215.3159	$215.32	$215.30	$215.30
Purchase #4	$147.59	4.284%	$153.9128	$153.91	$153.90	$153.90
Purchase #5	$137.60	11.687%	$153.6813	$153.68	$153.70	$153.70
Purchase #6	$143.52	10.442%	$158.5064	$158.51	$158.50	$158.50
Purchase #7	$126.91	12.292%	$142.5098	$142.51	$142.50	$142.50
7 purchase totals =	$866.49		$948.4793	$948.48	$948.45	$948.40