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	$118.86	7.795%	$128.1251	$128.13	$128.15	$128.10
Purchase #2	$76.35	8.249%	$82.6481	$82.65	$82.65	$82.60
Purchase #3	$156.77	13.789%	$178.387	$178.39	$178.40	$178.40
Purchase #4	$165.30	4.143%	$172.1484	$172.15	$172.15	$172.10
Purchase #5	$142.92	7.697%	$153.9206	$153.92	$153.90	$153.90
Purchase #6	$205.34	5.157%	$215.9294	$215.93	$215.95	$215.90
Purchase #7	$145.32	12.755%	$163.8556	$163.86	$163.85	$163.90
7 purchase totals =	$1,010.86		$1,095.0142	$1,095.03	$1,095.05	$1,094.90