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	$98.88	12.285%	$111.0274	$111.03	$111.05	$111.00
Purchase #2	$15.93	3.449%	$16.4794	$16.48	$16.50	$16.50
Purchase #3	$85.79	13.137%	$97.0602	$97.06	$97.05	$97.10
Purchase #4	$240.43	13.758%	$273.5084	$273.51	$273.50	$273.50
Purchase #5	$100.67	10.683%	$111.4246	$111.42	$111.40	$111.40
Purchase #6	$238.52	7.218%	$255.7364	$255.74	$255.75	$255.70
Purchase #7	$167.59	3.432%	$173.3417	$173.34	$173.35	$173.30
7 purchase totals =	$947.81		$1,038.5781	$1,038.58	$1,038.60	$1,038.50