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	$177.50	10.683%	$196.4623	$196.46	$196.45	$196.50
Purchase #2	$25.48	8.285%	$27.591	$27.59	$27.60	$27.60
Purchase #3	$33.51	10.272%	$36.9521	$36.95	$36.95	$37.00
Purchase #4	$115.99	9.837%	$127.3999	$127.40	$127.40	$127.40
Purchase #5	$216.77	12.170%	$243.1509	$243.15	$243.15	$243.20
Purchase #6	$74.69	12.259%	$83.8462	$83.85	$83.85	$83.80
Purchase #7	$138.29	7.399%	$148.5221	$148.52	$148.50	$148.50
7 purchase totals =	$782.23		$863.9245	$863.92	$863.90	$864.00