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	$198.47	8.279%	$214.9013	$214.90	$214.90	$214.90
Purchase #2	$137.43	4.811%	$144.0418	$144.04	$144.05	$144.00
Purchase #3	$74.78	10.521%	$82.6476	$82.65	$82.65	$82.60
Purchase #4	$40.97	9.865%	$45.0117	$45.01	$45.00	$45.00
Purchase #5	$192.63	3.426%	$199.2295	$199.23	$199.25	$199.20
Purchase #6	$236.83	11.790%	$264.7523	$264.75	$264.75	$264.80
Purchase #7	$101.29	10.334%	$111.7573	$111.76	$111.75	$111.80
7 purchase totals =	$982.40		$1,062.3415	$1,062.34	$1,062.35	$1,062.30