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	$204.71	8.678%	$222.4747	$222.47	$222.45	$222.50
Purchase #2	$217.35	13.670%	$247.0617	$247.06	$247.05	$247.10
Purchase #3	$88.51	11.687%	$98.8542	$98.85	$98.85	$98.90
Purchase #4	$38.78	13.601%	$44.0545	$44.05	$44.05	$44.10
Purchase #5	$44.80	11.806%	$50.0891	$50.09	$50.10	$50.10
Purchase #6	$88.68	11.659%	$99.0192	$99.02	$99.00	$99.00
Purchase #7	$237.60	10.850%	$263.3796	$263.38	$263.40	$263.40
7 purchase totals =	$920.43		$1,024.9330	$1,024.92	$1,024.90	$1,025.10