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	$98.94	6.717%	$105.5858	$105.59	$105.60	$105.60
Purchase #2	$18.58	6.139%	$19.7206	$19.72	$19.70	$19.70
Purchase #3	$110.37	11.322%	$122.8661	$122.87	$122.85	$122.90
Purchase #4	$76.82	6.837%	$82.0722	$82.07	$82.05	$82.10
Purchase #5	$150.37	4.336%	$156.89	$156.89	$156.90	$156.90
Purchase #6	$116.69	10.392%	$128.8164	$128.82	$128.80	$128.80
Purchase #7	$137.43	6.209%	$145.963	$145.96	$145.95	$146.00
7 purchase totals =	$709.20		$761.9141	$761.92	$761.85	$762.00