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	$132.33	7.552%	$142.3236	$142.32	$142.30	$142.30
Purchase #2	$59.90	11.636%	$66.87	$66.87	$66.85	$66.90
Purchase #3	$197.57	3.623%	$204.728	$204.73	$204.75	$204.70
Purchase #4	$69.65	4.347%	$72.6777	$72.68	$72.70	$72.70
Purchase #5	$99.72	13.588%	$113.27	$113.27	$113.25	$113.30
Purchase #6	$118.82	3.757%	$123.2841	$123.28	$123.30	$123.30
Purchase #7	$123.72	4.636%	$129.4557	$129.46	$129.45	$129.50
7 purchase totals =	$801.71		$852.6091	$852.61	$852.60	$852.70