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	$187.25	5.124%	$196.8447	$196.84	$196.85	$196.80
Purchase #2	$69.29	3.167%	$71.4844	$71.48	$71.50	$71.50
Purchase #3	$117.72	13.665%	$133.8064	$133.81	$133.80	$133.80
Purchase #4	$114.36	7.604%	$123.0559	$123.06	$123.05	$123.10
Purchase #5	$119.49	7.108%	$127.9833	$127.98	$128.00	$128.00
Purchase #6	$186.95	6.185%	$198.5129	$198.51	$198.50	$198.50
Purchase #7	$195.94	8.356%	$212.3127	$212.31	$212.30	$212.30
7 purchase totals =	$991.00		$1,064.0003	$1,063.99	$1,064.00	$1,064.00