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	$35.59	3.828%	$36.9524	$36.95	$36.95	$37.00
Purchase #2	$134.67	13.507%	$152.8599	$152.86	$152.85	$152.90
Purchase #3	$136.60	3.420%	$141.2717	$141.27	$141.25	$141.30
Purchase #4	$146.76	11.353%	$163.4217	$163.42	$163.40	$163.40
Purchase #5	$223.67	9.303%	$244.478	$244.48	$244.50	$244.50
Purchase #6	$238.94	6.451%	$254.354	$254.35	$254.35	$254.40
Purchase #7	$37.81	12.231%	$42.4345	$42.43	$42.45	$42.40
7 purchase totals =	$954.04		$1,035.7722	$1,035.76	$1,035.75	$1,035.90