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	$245.49	7.326%	$263.4746	$263.47	$263.45	$263.50
Purchase #2	$45.69	10.831%	$50.6387	$50.64	$50.65	$50.60
Purchase #3	$75.88	10.444%	$83.8049	$83.80	$83.80	$83.80
Purchase #4	$119.33	3.839%	$123.9111	$123.91	$123.90	$123.90
Purchase #5	$218.78	3.697%	$226.8683	$226.87	$226.85	$226.90
Purchase #6	$151.74	3.783%	$157.4803	$157.48	$157.50	$157.50
Purchase #7	$165.67	13.410%	$187.8863	$187.89	$187.90	$187.90
7 purchase totals =	$1,022.58		$1,094.0642	$1,094.06	$1,094.05	$1,094.10