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	$180.43	9.767%	$198.0526	$198.05	$198.05	$198.10
Purchase #2	$228.42	13.514%	$259.2887	$259.29	$259.30	$259.30
Purchase #3	$208.54	6.372%	$221.8282	$221.83	$221.85	$221.80
Purchase #4	$174.29	6.312%	$185.2912	$185.29	$185.30	$185.30
Purchase #5	$189.50	5.862%	$200.6085	$200.61	$200.60	$200.60
Purchase #6	$165.51	13.499%	$187.8522	$187.85	$187.85	$187.90
Purchase #7	$125.30	3.664%	$129.891	$129.89	$129.90	$129.90
7 purchase totals =	$1,271.99		$1,382.8124	$1,382.81	$1,382.85	$1,382.90