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	$141.70	11.544%	$158.0578	$158.06	$158.05	$158.10
Purchase #2	$90.59	11.322%	$100.8466	$100.85	$100.85	$100.80
Purchase #3	$45.33	11.298%	$50.4514	$50.45	$50.45	$50.50
Purchase #4	$109.34	12.798%	$123.3333	$123.33	$123.35	$123.30
Purchase #5	$103.74	8.867%	$112.9386	$112.94	$112.95	$112.90
Purchase #6	$21.84	12.610%	$24.594	$24.59	$24.60	$24.60
Purchase #7	$173.62	10.353%	$191.5949	$191.59	$191.60	$191.60
7 purchase totals =	$686.16		$761.8166	$761.81	$761.85	$761.80