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	$177.83	10.221%	$196.006	$196.01	$196.00	$196.00
Purchase #2	$228.74	10.627%	$253.0482	$253.05	$253.05	$253.00
Purchase #3	$63.66	13.823%	$72.4597	$72.46	$72.45	$72.50
Purchase #4	$33.29	6.667%	$35.5094	$35.51	$35.50	$35.50
Purchase #5	$84.74	4.291%	$88.3762	$88.38	$88.40	$88.40
Purchase #6	$152.27	6.260%	$161.8021	$161.80	$161.80	$161.80
Purchase #7	$50.50	6.214%	$53.6381	$53.64	$53.65	$53.60
7 purchase totals =	$791.03		$860.8397	$860.85	$860.85	$860.80