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	$241.78	5.734%	$255.6437	$255.64	$255.65	$255.60
Purchase #2	$5.66	11.139%	$6.2905	$6.29	$6.30	$6.30
Purchase #3	$53.56	13.179%	$60.6187	$60.62	$60.60	$60.60
Purchase #4	$43.59	3.417%	$45.0795	$45.08	$45.10	$45.10
Purchase #5	$237.68	5.684%	$251.1897	$251.19	$251.20	$251.20
Purchase #6	$229.26	13.149%	$259.4054	$259.41	$259.40	$259.40
Purchase #7	$119.90	13.461%	$136.0397	$136.04	$136.05	$136.00
7 purchase totals =	$931.43		$1,014.2672	$1,014.27	$1,014.30	$1,014.20