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	$111.88	4.248%	$116.6327	$116.63	$116.65	$116.60
Purchase #2	$16.55	12.121%	$18.556	$18.56	$18.55	$18.60
Purchase #3	$171.80	11.783%	$192.0432	$192.04	$192.05	$192.00
Purchase #4	$89.83	5.716%	$94.9647	$94.96	$94.95	$95.00
Purchase #5	$99.69	5.316%	$104.9895	$104.99	$105.00	$105.00
Purchase #6	$103.46	12.499%	$116.3915	$116.39	$116.40	$116.40
Purchase #7	$197.87	13.653%	$224.8852	$224.89	$224.90	$224.90
7 purchase totals =	$791.08		$868.4628	$868.46	$868.50	$868.50