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	$76.62	11.766%	$85.6351	$85.64	$85.65	$85.60
Purchase #2	$138.34	12.821%	$156.0766	$156.08	$156.10	$156.10
Purchase #3	$50.79	10.128%	$55.934	$55.93	$55.95	$55.90
Purchase #4	$51.80	11.677%	$57.8487	$57.85	$57.85	$57.80
Purchase #5	$24.40	6.106%	$25.8899	$25.89	$25.90	$25.90
Purchase #6	$61.92	3.599%	$64.1485	$64.15	$64.15	$64.10
Purchase #7	$228.70	8.388%	$247.8834	$247.88	$247.90	$247.90
7 purchase totals =	$632.57		$693.4162	$693.42	$693.50	$693.30