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	$196.75	4.742%	$206.0799	$206.08	$206.10	$206.10
Purchase #2	$191.97	4.384%	$200.386	$200.39	$200.40	$200.40
Purchase #3	$119.86	9.812%	$131.6207	$131.62	$131.60	$131.60
Purchase #4	$14.30	9.542%	$15.6645	$15.66	$15.65	$15.70
Purchase #5	$17.32	8.845%	$18.852	$18.85	$18.85	$18.90
Purchase #6	$238.66	11.787%	$266.7909	$266.79	$266.80	$266.80
Purchase #7	$95.33	5.715%	$100.7781	$100.78	$100.80	$100.80
7 purchase totals =	$874.19		$940.1721	$940.17	$940.20	$940.30