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	$84.51	12.513%	$95.0847	$95.08	$95.10	$95.10
Purchase #2	$29.41	3.686%	$30.4941	$30.49	$30.50	$30.50
Purchase #3	$80.49	12.868%	$90.8475	$90.85	$90.85	$90.80
Purchase #4	$176.50	3.379%	$182.4639	$182.46	$182.45	$182.50
Purchase #5	$27.55	6.393%	$29.3113	$29.31	$29.30	$29.30
Purchase #6	$134.37	8.473%	$145.7552	$145.76	$145.75	$145.80
Purchase #7	$145.98	3.841%	$151.5871	$151.59	$151.60	$151.60
7 purchase totals =	$678.81		$725.5438	$725.54	$725.55	$725.60