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	$201.76	6.791%	$215.4615	$215.46	$215.45	$215.50
Purchase #2	$67.34	6.391%	$71.6437	$71.64	$71.65	$71.60
Purchase #3	$200.37	4.190%	$208.7655	$208.77	$208.75	$208.80
Purchase #4	$246.84	5.722%	$260.9642	$260.96	$260.95	$261.00
Purchase #5	$216.68	10.686%	$239.8344	$239.83	$239.85	$239.80
Purchase #6	$52.49	5.153%	$55.1948	$55.19	$55.20	$55.20
Purchase #7	$89.94	9.493%	$98.478	$98.48	$98.50	$98.50
7 purchase totals =	$1,075.42		$1,150.3421	$1,150.33	$1,150.35	$1,150.40