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	$100.54	13.844%	$114.4588	$114.46	$114.45	$114.50
Purchase #2	$111.68	12.467%	$125.6031	$125.60	$125.60	$125.60
Purchase #3	$187.97	6.490%	$200.1693	$200.17	$200.15	$200.20
Purchase #4	$125.79	13.564%	$142.8522	$142.85	$142.85	$142.90
Purchase #5	$183.77	6.772%	$196.2149	$196.21	$196.20	$196.20
Purchase #6	$163.73	10.732%	$181.3015	$181.30	$181.30	$181.30
Purchase #7	$184.36	12.578%	$207.5488	$207.55	$207.55	$207.50
7 purchase totals =	$1,057.84		$1,168.1486	$1,168.14	$1,168.10	$1,168.20