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	$114.38	7.684%	$123.169	$123.17	$123.15	$123.20
Purchase #2	$148.60	5.587%	$156.9023	$156.90	$156.90	$156.90
Purchase #3	$100.68	8.856%	$109.5962	$109.60	$109.60	$109.60
Purchase #4	$204.64	12.306%	$229.823	$229.82	$229.80	$229.80
Purchase #5	$220.95	9.419%	$241.7613	$241.76	$241.75	$241.80
Purchase #6	$141.66	6.438%	$150.7801	$150.78	$150.80	$150.80
Purchase #7	$125.34	12.388%	$140.8671	$140.87	$140.85	$140.90
7 purchase totals =	$1,056.25		$1,152.8990	$1,152.90	$1,152.85	$1,153.00