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	$197.53	8.112%	$213.5536	$213.55	$213.55	$213.60
Purchase #2	$118.29	6.142%	$125.5554	$125.56	$125.55	$125.60
Purchase #3	$131.58	9.320%	$143.8433	$143.84	$143.85	$143.80
Purchase #4	$126.97	4.801%	$133.0658	$133.07	$133.05	$133.10
Purchase #5	$87.64	3.242%	$90.4813	$90.48	$90.50	$90.50
Purchase #6	$113.87	3.666%	$118.0445	$118.04	$118.05	$118.00
Purchase #7	$105.84	5.170%	$111.3119	$111.31	$111.30	$111.30
7 purchase totals =	$881.72		$935.8558	$935.85	$935.85	$935.90