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	$57.64	11.107%	$64.0421	$64.04	$64.05	$64.00
Purchase #2	$22.53	6.275%	$23.9438	$23.94	$23.95	$23.90
Purchase #3	$102.90	5.258%	$108.3105	$108.31	$108.30	$108.30
Purchase #4	$166.38	3.118%	$171.5677	$171.57	$171.55	$171.60
Purchase #5	$40.56	7.545%	$43.6203	$43.62	$43.60	$43.60
Purchase #6	$144.52	6.440%	$153.8271	$153.83	$153.85	$153.80
Purchase #7	$179.94	9.325%	$196.7194	$196.72	$196.70	$196.70
7 purchase totals =	$714.47		$762.0309	$762.03	$762.00	$761.90