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	$82.25	12.223%	$92.3034	$92.30	$92.30	$92.30
Purchase #2	$164.31	13.797%	$186.9799	$186.98	$187.00	$187.00
Purchase #3	$136.61	5.248%	$143.7793	$143.78	$143.80	$143.80
Purchase #4	$32.69	11.732%	$36.5252	$36.53	$36.55	$36.50
Purchase #5	$199.88	11.720%	$223.3059	$223.31	$223.30	$223.30
Purchase #6	$161.35	3.826%	$167.5233	$167.52	$167.50	$167.50
Purchase #7	$88.99	4.419%	$92.9225	$92.92	$92.90	$92.90
7 purchase totals =	$866.08		$943.3395	$943.34	$943.35	$943.30