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	$196.30	10.474%	$216.8605	$216.86	$216.85	$216.90
Purchase #2	$10.39	11.576%	$11.5927	$11.59	$11.60	$11.60
Purchase #3	$81.64	11.324%	$90.8849	$90.88	$90.90	$90.90
Purchase #4	$73.77	9.442%	$80.7354	$80.74	$80.75	$80.70
Purchase #5	$144.65	8.523%	$156.9785	$156.98	$157.00	$157.00
Purchase #6	$39.63	12.466%	$44.5703	$44.57	$44.55	$44.60
Purchase #7	$188.45	6.331%	$200.3808	$200.38	$200.40	$200.40
7 purchase totals =	$734.83		$802.0031	$802.00	$802.05	$802.10