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	$132.68	8.506%	$143.9658	$143.97	$143.95	$144.00
Purchase #2	$138.40	3.295%	$142.9603	$142.96	$142.95	$143.00
Purchase #3	$99.84	4.707%	$104.5395	$104.54	$104.55	$104.50
Purchase #4	$198.62	8.522%	$215.5464	$215.55	$215.55	$215.50
Purchase #5	$199.55	8.411%	$216.3342	$216.33	$216.35	$216.30
Purchase #6	$219.80	6.582%	$234.2672	$234.27	$234.25	$234.30
Purchase #7	$172.91	13.509%	$196.2684	$196.27	$196.25	$196.30
7 purchase totals =	$1,161.80		$1,253.8818	$1,253.89	$1,253.85	$1,253.90