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	$196.85	6.631%	$209.9031	$209.90	$209.90	$209.90
Purchase #2	$80.43	7.561%	$86.5113	$86.51	$86.50	$86.50
Purchase #3	$22.89	6.396%	$24.354	$24.35	$24.35	$24.40
Purchase #4	$27.82	7.696%	$29.961	$29.96	$29.95	$30.00
Purchase #5	$174.92	6.210%	$185.7825	$185.78	$185.80	$185.80
Purchase #6	$234.38	9.404%	$256.4211	$256.42	$256.40	$256.40
Purchase #7	$137.70	10.339%	$151.9368	$151.94	$151.95	$151.90
7 purchase totals =	$874.99		$944.8698	$944.86	$944.85	$944.90