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	$162.86	11.479%	$181.5547	$181.55	$181.55	$181.60
Purchase #2	$153.97	4.585%	$161.0295	$161.03	$161.05	$161.00
Purchase #3	$161.68	8.105%	$174.7842	$174.78	$174.80	$174.80
Purchase #4	$82.54	3.584%	$85.4982	$85.50	$85.50	$85.50
Purchase #5	$137.36	9.311%	$150.1496	$150.15	$150.15	$150.10
Purchase #6	$124.95	13.498%	$141.8158	$141.82	$141.80	$141.80
Purchase #7	$159.52	5.598%	$168.4499	$168.45	$168.45	$168.40
7 purchase totals =	$982.88		$1,063.2819	$1,063.28	$1,063.30	$1,063.20