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	$124.64	6.588%	$132.8513	$132.85	$132.85	$132.90
Purchase #2	$59.89	10.156%	$65.9724	$65.97	$65.95	$66.00
Purchase #3	$178.57	11.776%	$199.5984	$199.60	$199.60	$199.60
Purchase #4	$72.84	11.720%	$81.3768	$81.38	$81.40	$81.40
Purchase #5	$44.54	5.346%	$46.9211	$46.92	$46.90	$46.90
Purchase #6	$179.87	9.191%	$196.4019	$196.40	$196.40	$196.40
Purchase #7	$134.93	3.244%	$139.3071	$139.31	$139.30	$139.30
7 purchase totals =	$795.28		$862.4290	$862.43	$862.40	$862.50