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	$12.82	12.853%	$14.4678	$14.47	$14.45	$14.50
Purchase #2	$215.25	3.506%	$222.7967	$222.80	$222.80	$222.80
Purchase #3	$6.28	13.689%	$7.1397	$7.14	$7.15	$7.10
Purchase #4	$244.41	3.835%	$253.7831	$253.78	$253.80	$253.80
Purchase #5	$91.48	4.179%	$95.3029	$95.30	$95.30	$95.30
Purchase #6	$51.64	13.177%	$58.4446	$58.44	$58.45	$58.40
Purchase #7	$96.45	13.640%	$109.6058	$109.61	$109.60	$109.60
7 purchase totals =	$718.33		$761.5406	$761.54	$761.55	$761.50