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	$29.56	10.527%	$32.6718	$32.67	$32.65	$32.70
Purchase #2	$164.70	3.521%	$170.4991	$170.50	$170.50	$170.50
Purchase #3	$198.92	11.848%	$222.488	$222.49	$222.50	$222.50
Purchase #4	$25.43	11.435%	$28.3379	$28.34	$28.35	$28.30
Purchase #5	$156.72	6.651%	$167.1434	$167.14	$167.15	$167.10
Purchase #6	$227.52	12.873%	$256.8086	$256.81	$256.80	$256.80
Purchase #7	$241.52	5.628%	$255.1127	$255.11	$255.10	$255.10
7 purchase totals =	$1,044.37		$1,133.0615	$1,133.06	$1,133.05	$1,133.00