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	$13.42	4.527%	$14.0275	$14.03	$14.05	$14.00
Purchase #2	$217.59	11.418%	$242.4344	$242.43	$242.45	$242.40
Purchase #3	$23.60	3.457%	$24.4159	$24.42	$24.40	$24.40
Purchase #4	$158.82	4.874%	$166.5609	$166.56	$166.55	$166.60
Purchase #5	$135.45	9.606%	$148.4613	$148.46	$148.45	$148.50
Purchase #6	$219.87	11.582%	$245.3353	$245.34	$245.35	$245.30
Purchase #7	$238.55	8.864%	$259.6951	$259.70	$259.70	$259.70
7 purchase totals =	$1,007.30		$1,100.9304	$1,100.94	$1,100.95	$1,100.90