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	$158.33	13.640%	$179.9262	$179.93	$179.95	$179.90
Purchase #2	$84.89	5.410%	$89.4825	$89.48	$89.50	$89.50
Purchase #3	$29.62	5.729%	$31.3169	$31.32	$31.30	$31.30
Purchase #4	$89.38	7.767%	$96.3221	$96.32	$96.30	$96.30
Purchase #5	$14.36	11.295%	$15.982	$15.98	$16.00	$16.00
Purchase #6	$32.87	3.610%	$34.0566	$34.06	$34.05	$34.10
Purchase #7	$15.29	8.160%	$16.5377	$16.54	$16.55	$16.50
7 purchase totals =	$424.74		$463.6240	$463.63	$463.65	$463.60