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	$207.48	3.836%	$215.4389	$215.44	$215.45	$215.40
Purchase #2	$228.79	4.189%	$238.374	$238.37	$238.35	$238.40
Purchase #3	$37.78	5.594%	$39.8934	$39.89	$39.90	$39.90
Purchase #4	$162.86	5.807%	$172.3173	$172.32	$172.30	$172.30
Purchase #5	$190.65	12.524%	$214.527	$214.53	$214.55	$214.50
Purchase #6	$40.43	12.858%	$45.6285	$45.63	$45.65	$45.60
Purchase #7	$150.92	11.581%	$168.398	$168.40	$168.40	$168.40
7 purchase totals =	$1,018.91		$1,094.5771	$1,094.58	$1,094.60	$1,094.50