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	$87.40	10.381%	$96.473	$96.47	$96.45	$96.50
Purchase #2	$55.71	13.498%	$63.2297	$63.23	$63.25	$63.20
Purchase #3	$164.93	8.861%	$179.5444	$179.54	$179.55	$179.50
Purchase #4	$72.67	7.476%	$78.1028	$78.10	$78.10	$78.10
Purchase #5	$15.67	7.807%	$16.8934	$16.89	$16.90	$16.90
Purchase #6	$60.87	9.247%	$66.4986	$66.50	$66.50	$66.50
Purchase #7	$22.57	7.552%	$24.2745	$24.27	$24.25	$24.30
7 purchase totals =	$479.82		$525.0164	$525.00	$525.00	$525.00