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	$32.76	9.695%	$35.9361	$35.94	$35.95	$35.90
Purchase #2	$208.58	6.818%	$222.801	$222.80	$222.80	$222.80
Purchase #3	$82.38	8.394%	$89.295	$89.30	$89.30	$89.30
Purchase #4	$87.49	10.139%	$96.3606	$96.36	$96.35	$96.40
Purchase #5	$106.43	13.517%	$120.8161	$120.82	$120.80	$120.80
Purchase #6	$168.26	5.397%	$177.341	$177.34	$177.35	$177.30
Purchase #7	$20.52	5.245%	$21.5963	$21.60	$21.60	$21.60
7 purchase totals =	$706.42		$764.1461	$764.16	$764.15	$764.10