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	$65.55	4.600%	$68.5653	$68.57	$68.55	$68.60
Purchase #2	$11.32	10.712%	$12.5326	$12.53	$12.55	$12.50
Purchase #3	$172.94	8.444%	$187.5431	$187.54	$187.55	$187.50
Purchase #4	$162.53	6.332%	$172.8214	$172.82	$172.80	$172.80
Purchase #5	$79.74	11.850%	$89.1892	$89.19	$89.20	$89.20
Purchase #6	$217.43	13.583%	$246.9635	$246.96	$246.95	$247.00
Purchase #7	$228.32	8.803%	$248.419	$248.42	$248.40	$248.40
7 purchase totals =	$937.83		$1,026.0341	$1,026.03	$1,026.00	$1,026.00