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	$196.54	7.502%	$211.2844	$211.28	$211.30	$211.30
Purchase #2	$68.37	6.647%	$72.9146	$72.91	$72.90	$72.90
Purchase #3	$52.85	5.596%	$55.8075	$55.81	$55.80	$55.80
Purchase #4	$220.62	7.692%	$237.5901	$237.59	$237.60	$237.60
Purchase #5	$18.43	8.346%	$19.9682	$19.97	$19.95	$20.00
Purchase #6	$137.68	7.743%	$148.3406	$148.34	$148.35	$148.30
Purchase #7	$235.61	9.279%	$257.4723	$257.47	$257.45	$257.50
7 purchase totals =	$930.10		$1,003.3777	$1,003.37	$1,003.35	$1,003.40