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	$232.55	12.678%	$262.0327	$262.03	$262.05	$262.00
Purchase #2	$206.92	4.326%	$215.8714	$215.87	$215.85	$215.90
Purchase #3	$131.42	9.828%	$144.336	$144.34	$144.35	$144.30
Purchase #4	$228.51	11.763%	$255.3896	$255.39	$255.40	$255.40
Purchase #5	$29.60	7.492%	$31.8176	$31.82	$31.80	$31.80
Purchase #6	$104.91	9.725%	$115.1125	$115.11	$115.10	$115.10
Purchase #7	$130.74	10.361%	$144.286	$144.29	$144.30	$144.30
7 purchase totals =	$1,064.65		$1,168.8458	$1,168.85	$1,168.85	$1,168.80