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	$57.65	9.850%	$63.3285	$63.33	$63.35	$63.30
Purchase #2	$211.47	10.358%	$233.3741	$233.37	$233.35	$233.40
Purchase #3	$40.85	4.774%	$42.8002	$42.80	$42.80	$42.80
Purchase #4	$225.25	13.184%	$254.947	$254.95	$254.95	$254.90
Purchase #5	$211.86	5.442%	$223.3894	$223.39	$223.40	$223.40
Purchase #6	$77.81	7.458%	$83.6131	$83.61	$83.60	$83.60
Purchase #7	$57.64	9.783%	$63.2789	$63.28	$63.30	$63.30
7 purchase totals =	$882.53		$964.7312	$964.73	$964.75	$964.70