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	$60.42	4.175%	$62.9425	$62.94	$62.95	$62.90
Purchase #2	$136.89	11.768%	$152.9992	$153.00	$153.00	$153.00
Purchase #3	$139.63	5.757%	$147.6685	$147.67	$147.65	$147.70
Purchase #4	$197.61	13.105%	$223.5068	$223.51	$223.50	$223.50
Purchase #5	$247.60	3.621%	$256.5656	$256.57	$256.55	$256.60
Purchase #6	$186.66	5.145%	$196.2637	$196.26	$196.25	$196.30
Purchase #7	$164.64	5.292%	$173.3527	$173.35	$173.35	$173.40
7 purchase totals =	$1,133.45		$1,213.2990	$1,213.30	$1,213.25	$1,213.40