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	$214.52	10.742%	$237.5637	$237.56	$237.55	$237.60
Purchase #2	$150.71	10.765%	$166.9339	$166.93	$166.95	$166.90
Purchase #3	$158.76	5.677%	$167.7728	$167.77	$167.75	$167.80
Purchase #4	$77.98	5.540%	$82.3001	$82.30	$82.30	$82.30
Purchase #5	$85.53	13.200%	$96.82	$96.82	$96.80	$96.80
Purchase #6	$143.92	8.322%	$155.897	$155.90	$155.90	$155.90
Purchase #7	$35.95	12.306%	$40.374	$40.37	$40.35	$40.40
7 purchase totals =	$867.37		$947.6615	$947.65	$947.60	$947.70