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	$134.28	5.728%	$141.9716	$141.97	$141.95	$142.00
Purchase #2	$139.62	8.594%	$151.6189	$151.62	$151.60	$151.60
Purchase #3	$17.74	4.119%	$18.4707	$18.47	$18.45	$18.50
Purchase #4	$39.88	13.516%	$45.2702	$45.27	$45.25	$45.30
Purchase #5	$104.86	7.702%	$112.9363	$112.94	$112.95	$112.90
Purchase #6	$81.79	13.172%	$92.5634	$92.56	$92.55	$92.60
Purchase #7	$155.72	4.736%	$163.0949	$163.09	$163.10	$163.10
7 purchase totals =	$673.89		$725.9260	$725.92	$725.85	$726.00