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	$118.82	13.320%	$134.6468	$134.65	$134.65	$134.60
Purchase #2	$244.26	4.625%	$255.557	$255.56	$255.55	$255.60
Purchase #3	$242.34	6.574%	$258.2714	$258.27	$258.25	$258.30
Purchase #4	$176.44	4.162%	$183.7834	$183.78	$183.80	$183.80
Purchase #5	$61.89	6.534%	$65.9339	$65.93	$65.95	$65.90
Purchase #6	$11.82	6.307%	$12.5655	$12.57	$12.55	$12.60
Purchase #7	$100.69	3.322%	$104.0349	$104.03	$104.05	$104.00
7 purchase totals =	$956.26		$1,014.7929	$1,014.79	$1,014.80	$1,014.80