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	$221.70	7.379%	$238.0592	$238.06	$238.05	$238.10
Purchase #2	$95.46	9.128%	$104.1736	$104.17	$104.15	$104.20
Purchase #3	$172.52	3.513%	$178.5806	$178.58	$178.60	$178.60
Purchase #4	$107.44	6.663%	$114.5987	$114.60	$114.60	$114.60
Purchase #5	$116.48	9.549%	$127.6027	$127.60	$127.60	$127.60
Purchase #6	$186.44	12.689%	$210.0974	$210.10	$210.10	$210.10
Purchase #7	$160.80	10.376%	$177.4846	$177.48	$177.50	$177.50
7 purchase totals =	$1,060.84		$1,150.5968	$1,150.59	$1,150.60	$1,150.70