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	$201.92	4.803%	$211.6182	$211.62	$211.60	$211.60
Purchase #2	$20.69	5.595%	$21.8476	$21.85	$21.85	$21.80
Purchase #3	$56.66	5.654%	$59.8636	$59.86	$59.85	$59.90
Purchase #4	$227.46	10.743%	$251.896	$251.90	$251.90	$251.90
Purchase #5	$103.64	4.529%	$108.3339	$108.33	$108.35	$108.30
Purchase #6	$67.87	10.239%	$74.8192	$74.82	$74.80	$74.80
Purchase #7	$39.54	9.467%	$43.2833	$43.28	$43.30	$43.30
7 purchase totals =	$717.78		$771.6618	$771.66	$771.65	$771.60