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	$148.66	5.298%	$156.536	$156.54	$156.55	$156.50
Purchase #2	$11.43	6.440%	$12.1661	$12.17	$12.15	$12.20
Purchase #3	$168.85	4.733%	$176.8417	$176.84	$176.85	$176.80
Purchase #4	$247.34	13.533%	$280.8125	$280.81	$280.80	$280.80
Purchase #5	$150.30	7.701%	$161.8746	$161.87	$161.85	$161.90
Purchase #6	$76.79	11.781%	$85.8366	$85.84	$85.85	$85.80
Purchase #7	$151.75	11.679%	$169.4729	$169.47	$169.45	$169.50
7 purchase totals =	$955.12		$1,043.5404	$1,043.54	$1,043.50	$1,043.50