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	$177.59	10.632%	$196.4714	$196.47	$196.45	$196.50
Purchase #2	$190.96	7.505%	$205.2915	$205.29	$205.30	$205.30
Purchase #3	$174.75	8.868%	$190.2468	$190.25	$190.25	$190.20
Purchase #4	$250.25	4.462%	$261.4162	$261.42	$261.40	$261.40
Purchase #5	$53.92	11.178%	$59.9472	$59.95	$59.95	$59.90
Purchase #6	$51.29	7.809%	$55.2952	$55.30	$55.30	$55.30
Purchase #7	$214.44	3.724%	$222.4257	$222.43	$222.45	$222.40
7 purchase totals =	$1,113.20		$1,191.0940	$1,191.11	$1,191.10	$1,191.00