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	$127.96	10.218%	$141.035	$141.04	$141.05	$141.00
Purchase #2	$71.27	4.469%	$74.4551	$74.46	$74.45	$74.50
Purchase #3	$38.50	7.495%	$41.3856	$41.39	$41.40	$41.40
Purchase #4	$83.60	7.218%	$89.6342	$89.63	$89.65	$89.60
Purchase #5	$179.85	9.187%	$196.3728	$196.37	$196.35	$196.40
Purchase #6	$18.80	10.745%	$20.8201	$20.82	$20.80	$20.80
Purchase #7	$224.45	3.677%	$232.703	$232.70	$232.70	$232.70
7 purchase totals =	$744.43		$796.4058	$796.41	$796.40	$796.40