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	$114.70	10.632%	$126.8949	$126.89	$126.90	$126.90
Purchase #2	$12.63	6.131%	$13.4043	$13.40	$13.40	$13.40
Purchase #3	$115.99	10.854%	$128.5796	$128.58	$128.60	$128.60
Purchase #4	$205.71	8.718%	$223.6438	$223.64	$223.65	$223.60
Purchase #5	$29.56	6.377%	$31.445	$31.45	$31.45	$31.40
Purchase #6	$98.99	12.144%	$111.0113	$111.01	$111.00	$111.00
Purchase #7	$209.92	13.398%	$238.0451	$238.05	$238.05	$238.00
7 purchase totals =	$787.50		$873.0240	$873.02	$873.05	$872.90