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	$173.36	12.246%	$194.5897	$194.59	$194.60	$194.60
Purchase #2	$38.87	10.718%	$43.0361	$43.04	$43.05	$43.00
Purchase #3	$139.58	13.532%	$158.468	$158.47	$158.45	$158.50
Purchase #4	$16.34	12.267%	$18.3444	$18.34	$18.35	$18.30
Purchase #5	$93.31	3.442%	$96.5217	$96.52	$96.50	$96.50
Purchase #6	$24.63	11.795%	$27.5351	$27.54	$27.55	$27.50
Purchase #7	$82.62	4.688%	$86.4932	$86.49	$86.50	$86.50
7 purchase totals =	$568.71		$624.9882	$624.99	$625.00	$624.90