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	$119.85	11.666%	$133.8317	$133.83	$133.85	$133.80
Purchase #2	$179.29	5.811%	$189.7085	$189.71	$189.70	$189.70
Purchase #3	$96.63	9.118%	$105.4407	$105.44	$105.45	$105.40
Purchase #4	$156.76	3.631%	$162.452	$162.45	$162.45	$162.50
Purchase #5	$158.31	10.285%	$174.5922	$174.59	$174.60	$174.60
Purchase #6	$98.82	8.732%	$107.449	$107.45	$107.45	$107.40
Purchase #7	$141.78	11.580%	$158.1981	$158.20	$158.20	$158.20
7 purchase totals =	$951.44		$1,031.6722	$1,031.67	$1,031.70	$1,031.60