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	$154.60	8.333%	$167.4828	$167.48	$167.50	$167.50
Purchase #2	$240.96	8.730%	$261.9958	$262.00	$262.00	$262.00
Purchase #3	$31.36	3.215%	$32.3682	$32.37	$32.35	$32.40
Purchase #4	$186.73	6.494%	$198.8562	$198.86	$198.85	$198.90
Purchase #5	$88.69	13.226%	$100.4201	$100.42	$100.40	$100.40
Purchase #6	$218.91	8.714%	$237.9858	$237.99	$238.00	$238.00
Purchase #7	$231.56	10.717%	$256.3763	$256.38	$256.40	$256.40
7 purchase totals =	$1,152.81		$1,255.4852	$1,255.50	$1,255.50	$1,255.60