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	$196.69	12.488%	$221.2526	$221.25	$221.25	$221.30
Purchase #2	$144.70	12.332%	$162.5444	$162.54	$162.55	$162.50
Purchase #3	$67.54	3.642%	$69.9998	$70.00	$70.00	$70.00
Purchase #4	$152.92	8.225%	$165.4977	$165.50	$165.50	$165.50
Purchase #5	$40.28	10.392%	$44.4659	$44.47	$44.45	$44.50
Purchase #6	$160.41	5.676%	$169.5149	$169.51	$169.50	$169.50
Purchase #7	$47.70	9.833%	$52.3903	$52.39	$52.40	$52.40
7 purchase totals =	$810.24		$885.6656	$885.66	$885.65	$885.70