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	$68.38	6.260%	$72.6606	$72.66	$72.65	$72.70
Purchase #2	$85.84	11.194%	$95.4489	$95.45	$95.45	$95.40
Purchase #3	$117.83	12.246%	$132.2595	$132.26	$132.25	$132.30
Purchase #4	$186.57	5.517%	$196.8631	$196.86	$196.85	$196.90
Purchase #5	$59.72	6.262%	$63.4597	$63.46	$63.45	$63.50
Purchase #6	$195.88	11.153%	$217.7265	$217.73	$217.75	$217.70
Purchase #7	$65.27	6.344%	$69.4107	$69.41	$69.40	$69.40
7 purchase totals =	$779.49		$847.8290	$847.83	$847.80	$847.90