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	$214.74	3.673%	$222.6274	$222.63	$222.65	$222.60
Purchase #2	$117.91	11.405%	$131.3576	$131.36	$131.35	$131.40
Purchase #3	$175.69	3.818%	$182.3978	$182.40	$182.40	$182.40
Purchase #4	$248.60	8.520%	$269.7807	$269.78	$269.80	$269.80
Purchase #5	$74.55	11.458%	$83.0919	$83.09	$83.10	$83.10
Purchase #6	$76.98	4.665%	$80.5711	$80.57	$80.55	$80.60
Purchase #7	$108.28	7.549%	$116.4541	$116.45	$116.45	$116.50
7 purchase totals =	$1,016.75		$1,086.2806	$1,086.28	$1,086.30	$1,086.40