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	$139.47	3.200%	$143.933	$143.93	$143.95	$143.90
Purchase #2	$18.91	13.707%	$21.502	$21.50	$21.50	$21.50
Purchase #3	$208.95	7.493%	$224.6066	$224.61	$224.60	$224.60
Purchase #4	$129.59	13.237%	$146.7438	$146.74	$146.75	$146.70
Purchase #5	$168.64	5.548%	$177.9961	$178.00	$178.00	$178.00
Purchase #6	$219.32	3.197%	$226.3317	$226.33	$226.35	$226.30
Purchase #7	$98.61	7.382%	$105.8894	$105.89	$105.90	$105.90
7 purchase totals =	$983.49		$1,047.0026	$1,047.00	$1,047.05	$1,046.90