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	$162.38	8.154%	$175.6205	$175.62	$175.60	$175.60
Purchase #2	$142.73	7.564%	$153.5261	$153.53	$153.55	$153.50
Purchase #3	$133.65	7.664%	$143.8929	$143.89	$143.90	$143.90
Purchase #4	$222.86	5.137%	$234.3083	$234.31	$234.30	$234.30
Purchase #5	$220.83	11.388%	$245.9781	$245.98	$246.00	$246.00
Purchase #6	$214.85	12.852%	$242.4625	$242.46	$242.45	$242.50
Purchase #7	$228.57	12.314%	$256.7161	$256.72	$256.70	$256.70
7 purchase totals =	$1,325.87		$1,452.5045	$1,452.51	$1,452.50	$1,452.50