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	$132.94	11.374%	$148.0606	$148.06	$148.05	$148.10
Purchase #2	$123.35	10.624%	$136.4547	$136.45	$136.45	$136.50
Purchase #3	$136.31	5.855%	$144.291	$144.29	$144.30	$144.30
Purchase #4	$127.74	13.119%	$144.4982	$144.50	$144.50	$144.50
Purchase #5	$100.72	13.588%	$114.4058	$114.41	$114.40	$114.40
Purchase #6	$92.50	9.576%	$101.3578	$101.36	$101.35	$101.40
Purchase #7	$164.97	5.805%	$174.5465	$174.55	$174.55	$174.50
7 purchase totals =	$878.53		$963.6146	$963.62	$963.60	$963.70