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	$238.43	10.102%	$262.5162	$262.52	$262.50	$262.50
Purchase #2	$189.90	9.782%	$208.476	$208.48	$208.50	$208.50
Purchase #3	$250.82	9.505%	$274.6604	$274.66	$274.65	$274.70
Purchase #4	$31.51	3.284%	$32.5448	$32.54	$32.55	$32.50
Purchase #5	$201.82	7.308%	$216.569	$216.57	$216.55	$216.60
Purchase #6	$24.93	5.342%	$26.2618	$26.26	$26.25	$26.30
Purchase #7	$37.54	13.396%	$42.5689	$42.57	$42.55	$42.60
7 purchase totals =	$974.95		$1,063.5971	$1,063.60	$1,063.55	$1,063.70