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	$143.71	7.433%	$154.392	$154.39	$154.40	$154.40
Purchase #2	$29.70	5.661%	$31.3813	$31.38	$31.40	$31.40
Purchase #3	$199.40	4.584%	$208.5405	$208.54	$208.55	$208.50
Purchase #4	$123.52	7.483%	$132.763	$132.76	$132.75	$132.80
Purchase #5	$243.30	11.204%	$270.5593	$270.56	$270.55	$270.60
Purchase #6	$26.39	3.870%	$27.4113	$27.41	$27.40	$27.40
Purchase #7	$226.83	8.439%	$245.9722	$245.97	$245.95	$246.00
7 purchase totals =	$992.85		$1,071.0196	$1,071.01	$1,071.00	$1,071.10