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	$225.33	7.638%	$242.5407	$242.54	$242.55	$242.50
Purchase #2	$215.33	5.828%	$227.8794	$227.88	$227.90	$227.90
Purchase #3	$144.60	13.585%	$164.2439	$164.24	$164.25	$164.20
Purchase #4	$66.42	7.417%	$71.3464	$71.35	$71.35	$71.30
Purchase #5	$84.54	11.574%	$94.3247	$94.32	$94.30	$94.30
Purchase #6	$105.29	6.240%	$111.8601	$111.86	$111.85	$111.90
Purchase #7	$177.65	13.650%	$201.8992	$201.90	$201.90	$201.90
7 purchase totals =	$1,019.16		$1,114.0944	$1,114.09	$1,114.10	$1,114.00