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	$204.27	11.826%	$228.427	$228.43	$228.45	$228.40
Purchase #2	$7.56	3.710%	$7.8405	$7.84	$7.85	$7.80
Purchase #3	$28.54	11.423%	$31.8001	$31.80	$31.80	$31.80
Purchase #4	$39.28	9.125%	$42.8643	$42.86	$42.85	$42.90
Purchase #5	$151.34	12.141%	$169.7142	$169.71	$169.70	$169.70
Purchase #6	$24.59	4.701%	$25.746	$25.75	$25.75	$25.70
Purchase #7	$213.81	4.221%	$222.8349	$222.83	$222.85	$222.80
7 purchase totals =	$669.39		$729.2270	$729.22	$729.25	$729.10