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	$97.79	4.235%	$101.9314	$101.93	$101.95	$101.90
Purchase #2	$30.66	9.208%	$33.4832	$33.48	$33.50	$33.50
Purchase #3	$190.32	3.194%	$196.3988	$196.40	$196.40	$196.40
Purchase #4	$50.33	13.631%	$57.1905	$57.19	$57.20	$57.20
Purchase #5	$231.45	13.390%	$262.4412	$262.44	$262.45	$262.40
Purchase #6	$208.49	7.184%	$223.4679	$223.47	$223.45	$223.50
Purchase #7	$204.52	10.532%	$226.06	$226.06	$226.05	$226.10
7 purchase totals =	$1,013.56		$1,100.9730	$1,100.97	$1,101.00	$1,101.00