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	$179.28	9.119%	$195.6285	$195.63	$195.65	$195.60
Purchase #2	$71.39	12.540%	$80.3423	$80.34	$80.35	$80.30
Purchase #3	$71.53	8.787%	$77.8153	$77.82	$77.80	$77.80
Purchase #4	$140.53	12.725%	$158.4124	$158.41	$158.40	$158.40
Purchase #5	$95.36	5.294%	$100.4084	$100.41	$100.40	$100.40
Purchase #6	$246.39	12.668%	$277.6027	$277.60	$277.60	$277.60
Purchase #7	$65.99	9.496%	$72.2564	$72.26	$72.25	$72.30
7 purchase totals =	$870.47		$962.4660	$962.47	$962.45	$962.40