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	$13.28	7.218%	$14.2386	$14.24	$14.25	$14.20
Purchase #2	$48.90	13.549%	$55.5255	$55.53	$55.55	$55.50
Purchase #3	$201.67	3.129%	$207.9803	$207.98	$208.00	$208.00
Purchase #4	$230.33	5.294%	$242.5237	$242.52	$242.50	$242.50
Purchase #5	$164.67	4.822%	$172.6104	$172.61	$172.60	$172.60
Purchase #6	$99.87	11.626%	$111.4809	$111.48	$111.50	$111.50
Purchase #7	$119.41	3.442%	$123.5201	$123.52	$123.50	$123.50
7 purchase totals =	$878.13		$927.8795	$927.88	$927.90	$927.80