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	$153.66	3.376%	$158.8476	$158.85	$158.85	$158.80
Purchase #2	$206.41	3.588%	$213.816	$213.82	$213.80	$213.80
Purchase #3	$168.87	10.684%	$186.9121	$186.91	$186.90	$186.90
Purchase #4	$219.60	6.492%	$233.8564	$233.86	$233.85	$233.90
Purchase #5	$28.51	6.468%	$30.354	$30.35	$30.35	$30.40
Purchase #6	$52.73	5.756%	$55.7651	$55.77	$55.75	$55.80
Purchase #7	$124.45	10.295%	$137.2621	$137.26	$137.25	$137.30
7 purchase totals =	$954.23		$1,016.8133	$1,016.82	$1,016.75	$1,016.90