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	$59.47	7.510%	$63.9362	$63.94	$63.95	$63.90
Purchase #2	$81.49	13.596%	$92.5694	$92.57	$92.55	$92.60
Purchase #3	$34.60	7.788%	$37.2946	$37.29	$37.30	$37.30
Purchase #4	$90.45	13.616%	$102.7657	$102.77	$102.75	$102.80
Purchase #5	$171.50	4.113%	$178.5538	$178.55	$178.55	$178.60
Purchase #6	$72.45	11.760%	$80.9701	$80.97	$80.95	$81.00
Purchase #7	$151.71	13.466%	$172.1393	$172.14	$172.15	$172.10
7 purchase totals =	$661.67		$728.2291	$728.23	$728.20	$728.30