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	$59.67	4.680%	$62.4626	$62.46	$62.45	$62.50
Purchase #2	$83.36	8.335%	$90.3081	$90.31	$90.30	$90.30
Purchase #3	$145.99	8.411%	$158.2692	$158.27	$158.25	$158.30
Purchase #4	$119.90	10.788%	$132.8348	$132.83	$132.85	$132.80
Purchase #5	$174.37	10.355%	$192.426	$192.43	$192.45	$192.40
Purchase #6	$15.83	12.714%	$17.8426	$17.84	$17.85	$17.80
Purchase #7	$168.29	6.787%	$179.7118	$179.71	$179.70	$179.70
7 purchase totals =	$767.41		$833.8551	$833.85	$833.85	$833.80