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	$94.80	9.370%	$103.6828	$103.68	$103.70	$103.70
Purchase #2	$150.78	7.550%	$162.1639	$162.16	$162.15	$162.20
Purchase #3	$28.76	7.562%	$30.9348	$30.93	$30.95	$30.90
Purchase #4	$84.43	7.292%	$90.5866	$90.59	$90.60	$90.60
Purchase #5	$224.77	5.681%	$237.5392	$237.54	$237.55	$237.50
Purchase #6	$51.59	7.237%	$55.3236	$55.32	$55.30	$55.30
Purchase #7	$126.30	6.466%	$134.4666	$134.47	$134.45	$134.50
7 purchase totals =	$761.43		$814.6975	$814.69	$814.70	$814.70