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	$70.95	7.691%	$76.4068	$76.41	$76.40	$76.40
Purchase #2	$44.50	10.738%	$49.2784	$49.28	$49.30	$49.30
Purchase #3	$82.31	4.545%	$86.051	$86.05	$86.05	$86.10
Purchase #4	$89.42	4.264%	$93.2329	$93.23	$93.25	$93.20
Purchase #5	$107.69	8.193%	$116.513	$116.51	$116.50	$116.50
Purchase #6	$111.49	5.421%	$117.5339	$117.53	$117.55	$117.50
Purchase #7	$85.32	4.597%	$89.2422	$89.24	$89.25	$89.20
7 purchase totals =	$591.68		$628.2582	$628.25	$628.30	$628.20