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	$209.71	4.440%	$219.0211	$219.02	$219.00	$219.00
Purchase #2	$221.76	3.239%	$228.9428	$228.94	$228.95	$228.90
Purchase #3	$126.75	3.411%	$131.0734	$131.07	$131.05	$131.10
Purchase #4	$231.51	11.715%	$258.6314	$258.63	$258.65	$258.60
Purchase #5	$187.52	3.752%	$194.5558	$194.56	$194.55	$194.60
Purchase #6	$45.61	4.203%	$47.527	$47.53	$47.55	$47.50
Purchase #7	$75.59	13.235%	$85.5943	$85.59	$85.60	$85.60
7 purchase totals =	$1,098.45		$1,165.3458	$1,165.34	$1,165.35	$1,165.30