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	$126.95	13.121%	$143.6071	$143.61	$143.60	$143.60
Purchase #2	$11.47	12.793%	$12.9374	$12.94	$12.95	$12.90
Purchase #3	$139.56	10.747%	$154.5585	$154.56	$154.55	$154.60
Purchase #4	$129.52	9.626%	$141.9876	$141.99	$142.00	$142.00
Purchase #5	$235.86	4.856%	$247.3134	$247.31	$247.30	$247.30
Purchase #6	$25.89	9.293%	$28.296	$28.30	$28.30	$28.30
Purchase #7	$210.60	13.437%	$238.8983	$238.90	$238.90	$238.90
7 purchase totals =	$879.85		$967.5983	$967.61	$967.60	$967.60