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	$87.42	9.224%	$95.4836	$95.48	$95.50	$95.50
Purchase #2	$179.72	4.616%	$188.0159	$188.02	$188.00	$188.00
Purchase #3	$195.60	5.264%	$205.8964	$205.90	$205.90	$205.90
Purchase #4	$89.81	6.802%	$95.9189	$95.92	$95.90	$95.90
Purchase #5	$237.78	10.312%	$262.2999	$262.30	$262.30	$262.30
Purchase #6	$113.47	5.214%	$119.3863	$119.39	$119.40	$119.40
Purchase #7	$43.97	10.404%	$48.5446	$48.54	$48.55	$48.50
7 purchase totals =	$947.77		$1,015.5456	$1,015.55	$1,015.55	$1,015.50