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	$119.70	5.612%	$126.4176	$126.42	$126.40	$126.40
Purchase #2	$152.92	12.152%	$171.5028	$171.50	$171.50	$171.50
Purchase #3	$85.68	5.655%	$90.5252	$90.53	$90.55	$90.50
Purchase #4	$69.87	7.105%	$74.8343	$74.83	$74.85	$74.80
Purchase #5	$39.90	4.255%	$41.5977	$41.60	$41.60	$41.60
Purchase #6	$33.27	3.777%	$34.5266	$34.53	$34.55	$34.50
Purchase #7	$198.55	13.138%	$224.6355	$224.64	$224.65	$224.60
7 purchase totals =	$699.89		$764.0397	$764.05	$764.10	$763.90