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	$179.71	11.324%	$200.0604	$200.06	$200.05	$200.10
Purchase #2	$188.66	12.308%	$211.8803	$211.88	$211.90	$211.90
Purchase #3	$111.68	4.770%	$117.0071	$117.01	$117.00	$117.00
Purchase #4	$196.78	9.301%	$215.0825	$215.08	$215.10	$215.10
Purchase #5	$19.94	8.216%	$21.5783	$21.58	$21.60	$21.60
Purchase #6	$218.52	7.256%	$234.3758	$234.38	$234.40	$234.40
Purchase #7	$180.36	11.367%	$200.8615	$200.86	$200.85	$200.90
7 purchase totals =	$1,095.65		$1,200.8459	$1,200.85	$1,200.90	$1,201.00