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	$218.89	3.838%	$227.291	$227.29	$227.30	$227.30
Purchase #2	$32.58	11.278%	$36.2544	$36.25	$36.25	$36.30
Purchase #3	$43.36	4.405%	$45.27	$45.27	$45.25	$45.30
Purchase #4	$8.49	5.427%	$8.9508	$8.95	$8.95	$9.00
Purchase #5	$95.83	10.383%	$105.78	$105.78	$105.80	$105.80
Purchase #6	$216.58	13.372%	$245.5411	$245.54	$245.55	$245.50
Purchase #7	$48.45	11.645%	$54.092	$54.09	$54.10	$54.10
7 purchase totals =	$664.18		$723.1793	$723.17	$723.20	$723.30