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	$136.64	8.734%	$148.5741	$148.57	$148.55	$148.60
Purchase #2	$219.48	11.322%	$244.3295	$244.33	$244.35	$244.30
Purchase #3	$37.66	3.178%	$38.8568	$38.86	$38.85	$38.90
Purchase #4	$229.25	13.344%	$259.8411	$259.84	$259.85	$259.80
Purchase #5	$114.95	11.233%	$127.8623	$127.86	$127.85	$127.90
Purchase #6	$104.79	13.206%	$118.6286	$118.63	$118.65	$118.60
Purchase #7	$78.94	10.203%	$86.9942	$86.99	$87.00	$87.00
7 purchase totals =	$921.71		$1,025.0866	$1,025.08	$1,025.10	$1,025.10