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	$49.83	7.183%	$53.4093	$53.41	$53.40	$53.40
Purchase #2	$94.97	5.631%	$100.3178	$100.32	$100.30	$100.30
Purchase #3	$38.68	4.523%	$40.4295	$40.43	$40.45	$40.40
Purchase #4	$47.37	7.832%	$51.08	$51.08	$51.10	$51.10
Purchase #5	$53.97	10.659%	$59.7227	$59.72	$59.70	$59.70
Purchase #6	$146.43	5.224%	$154.0795	$154.08	$154.10	$154.10
Purchase #7	$226.56	9.484%	$248.047	$248.05	$248.05	$248.00
7 purchase totals =	$657.81		$707.0858	$707.09	$707.10	$707.00