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	$247.59	10.583%	$273.7924	$273.79	$273.80	$273.80
Purchase #2	$13.51	5.497%	$14.2526	$14.25	$14.25	$14.30
Purchase #3	$122.90	3.496%	$127.1966	$127.20	$127.20	$127.20
Purchase #4	$228.51	12.846%	$257.8644	$257.86	$257.85	$257.90
Purchase #5	$161.75	4.272%	$168.66	$168.66	$168.65	$168.70
Purchase #6	$214.89	7.280%	$230.534	$230.53	$230.55	$230.50
Purchase #7	$20.89	9.490%	$22.8725	$22.87	$22.85	$22.90
7 purchase totals =	$1,010.04		$1,095.1725	$1,095.16	$1,095.15	$1,095.30