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	$202.56	5.171%	$213.0344	$213.03	$213.05	$213.00
Purchase #2	$10.29	13.556%	$11.6849	$11.68	$11.70	$11.70
Purchase #3	$241.94	10.754%	$267.9582	$267.96	$267.95	$268.00
Purchase #4	$117.39	5.517%	$123.8664	$123.87	$123.85	$123.90
Purchase #5	$132.69	9.178%	$144.8683	$144.87	$144.85	$144.90
Purchase #6	$197.49	12.719%	$222.6088	$222.61	$222.60	$222.60
Purchase #7	$169.51	9.219%	$185.1371	$185.14	$185.15	$185.10
7 purchase totals =	$1,071.87		$1,169.1581	$1,169.16	$1,169.15	$1,169.20