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	$192.68	4.188%	$200.7494	$200.75	$200.75	$200.70
Purchase #2	$123.47	6.517%	$131.5165	$131.52	$131.50	$131.50
Purchase #3	$121.85	4.523%	$127.3613	$127.36	$127.35	$127.40
Purchase #4	$117.58	10.487%	$129.9106	$129.91	$129.90	$129.90
Purchase #5	$51.54	5.646%	$54.4499	$54.45	$54.45	$54.40
Purchase #6	$169.81	5.104%	$178.4771	$178.48	$178.50	$178.50
Purchase #7	$206.97	8.546%	$224.6577	$224.66	$224.65	$224.70
7 purchase totals =	$983.90		$1,047.1225	$1,047.13	$1,047.10	$1,047.10