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	$216.57	9.228%	$236.5551	$236.56	$236.55	$236.60
Purchase #2	$181.52	7.748%	$195.5842	$195.58	$195.60	$195.60
Purchase #3	$56.80	5.479%	$59.9121	$59.91	$59.90	$59.90
Purchase #4	$106.82	7.795%	$115.1466	$115.15	$115.15	$115.10
Purchase #5	$118.64	4.409%	$123.8708	$123.87	$123.85	$123.90
Purchase #6	$217.80	7.856%	$234.9104	$234.91	$234.90	$234.90
Purchase #7	$45.54	3.167%	$46.9823	$46.98	$47.00	$47.00
7 purchase totals =	$943.69		$1,012.9615	$1,012.96	$1,012.95	$1,013.00