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	$59.27	5.582%	$62.5785	$62.58	$62.60	$62.60
Purchase #2	$13.74	13.824%	$15.6394	$15.64	$15.65	$15.60
Purchase #3	$156.39	12.577%	$176.0592	$176.06	$176.05	$176.10
Purchase #4	$79.75	12.211%	$89.4883	$89.49	$89.50	$89.50
Purchase #5	$212.37	11.829%	$237.4912	$237.49	$237.50	$237.50
Purchase #6	$186.90	6.334%	$198.7382	$198.74	$198.75	$198.70
Purchase #7	$192.48	12.465%	$216.4726	$216.47	$216.45	$216.50
7 purchase totals =	$900.90		$996.4674	$996.47	$996.50	$996.50