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	$216.56	7.806%	$233.4647	$233.46	$233.45	$233.50
Purchase #2	$26.87	10.177%	$29.6046	$29.60	$29.60	$29.60
Purchase #3	$31.33	8.161%	$33.8868	$33.89	$33.90	$33.90
Purchase #4	$111.74	4.167%	$116.3962	$116.40	$116.40	$116.40
Purchase #5	$178.47	5.841%	$188.8944	$188.89	$188.90	$188.90
Purchase #6	$215.29	13.736%	$244.8622	$244.86	$244.85	$244.90
Purchase #7	$87.48	10.713%	$96.8517	$96.85	$96.85	$96.90
7 purchase totals =	$867.74		$943.9606	$943.95	$943.95	$944.10