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	$13.50	3.577%	$13.9829	$13.98	$14.00	$14.00
Purchase #2	$130.57	12.351%	$146.6967	$146.70	$146.70	$146.70
Purchase #3	$67.53	6.709%	$72.0606	$72.06	$72.05	$72.10
Purchase #4	$61.34	9.558%	$67.2029	$67.20	$67.20	$67.20
Purchase #5	$192.48	3.567%	$199.3458	$199.35	$199.35	$199.30
Purchase #6	$123.54	3.454%	$127.8071	$127.81	$127.80	$127.80
Purchase #7	$225.90	5.547%	$238.4307	$238.43	$238.45	$238.40
7 purchase totals =	$814.86		$865.5267	$865.53	$865.55	$865.50