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	$103.33	10.334%	$114.0081	$114.01	$114.00	$114.00
Purchase #2	$115.91	4.795%	$121.4679	$121.47	$121.45	$121.50
Purchase #3	$212.77	13.858%	$242.2557	$242.26	$242.25	$242.30
Purchase #4	$41.87	3.808%	$43.4644	$43.46	$43.45	$43.50
Purchase #5	$104.51	9.337%	$114.2681	$114.27	$114.25	$114.30
Purchase #6	$170.48	8.777%	$185.443	$185.44	$185.45	$185.40
Purchase #7	$138.59	13.626%	$157.4743	$157.47	$157.45	$157.50
7 purchase totals =	$887.46		$978.3815	$978.38	$978.30	$978.50