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	$12.32	13.248%	$13.9522	$13.95	$13.95	$14.00
Purchase #2	$57.66	3.847%	$59.8782	$59.88	$59.90	$59.90
Purchase #3	$164.38	7.300%	$176.3797	$176.38	$176.40	$176.40
Purchase #4	$236.67	12.148%	$265.4207	$265.42	$265.40	$265.40
Purchase #5	$238.63	13.478%	$270.7926	$270.79	$270.80	$270.80
Purchase #6	$158.53	12.166%	$177.8168	$177.82	$177.80	$177.80
Purchase #7	$101.58	9.446%	$111.1752	$111.18	$111.20	$111.20
7 purchase totals =	$969.77		$1,075.4154	$1,075.42	$1,075.45	$1,075.50