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	$163.53	5.713%	$172.8725	$172.87	$172.85	$172.90
Purchase #2	$232.72	11.128%	$258.6171	$258.62	$258.60	$258.60
Purchase #3	$172.98	3.863%	$179.6622	$179.66	$179.65	$179.70
Purchase #4	$184.51	12.684%	$207.9132	$207.91	$207.90	$207.90
Purchase #5	$131.96	11.284%	$146.8504	$146.85	$146.85	$146.90
Purchase #6	$39.41	6.423%	$41.9413	$41.94	$41.95	$41.90
Purchase #7	$198.89	13.564%	$225.8674	$225.87	$225.85	$225.90
7 purchase totals =	$1,124.00		$1,233.7241	$1,233.72	$1,233.65	$1,233.80