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	$53.89	10.714%	$59.6638	$59.66	$59.65	$59.70
Purchase #2	$194.30	12.309%	$218.2164	$218.22	$218.20	$218.20
Purchase #3	$63.75	3.491%	$65.9755	$65.98	$66.00	$66.00
Purchase #4	$113.72	11.471%	$126.7648	$126.76	$126.75	$126.80
Purchase #5	$190.78	9.772%	$209.423	$209.42	$209.40	$209.40
Purchase #6	$180.53	5.645%	$190.7209	$190.72	$190.70	$190.70
Purchase #7	$172.32	3.374%	$178.1341	$178.13	$178.15	$178.10
7 purchase totals =	$969.29		$1,048.8985	$1,048.89	$1,048.85	$1,048.90