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	$78.60	10.715%	$87.022	$87.02	$87.00	$87.00
Purchase #2	$78.75	6.523%	$83.8869	$83.89	$83.90	$83.90
Purchase #3	$186.94	12.396%	$210.1131	$210.11	$210.10	$210.10
Purchase #4	$198.75	4.818%	$208.3258	$208.33	$208.35	$208.30
Purchase #5	$197.48	5.271%	$207.8892	$207.89	$207.90	$207.90
Purchase #6	$187.60	4.763%	$196.5354	$196.54	$196.55	$196.50
Purchase #7	$116.64	10.144%	$128.472	$128.47	$128.45	$128.50
7 purchase totals =	$1,044.76		$1,122.2444	$1,122.25	$1,122.25	$1,122.20