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	$115.92	9.874%	$127.3659	$127.37	$127.35	$127.40
Purchase #2	$14.96	3.278%	$15.4504	$15.45	$15.45	$15.50
Purchase #3	$42.40	9.440%	$46.4026	$46.40	$46.40	$46.40
Purchase #4	$132.46	11.684%	$147.9366	$147.94	$147.95	$147.90
Purchase #5	$164.28	5.266%	$172.931	$172.93	$172.95	$172.90
Purchase #6	$86.65	6.194%	$92.0171	$92.02	$92.00	$92.00
Purchase #7	$241.92	12.819%	$272.9317	$272.93	$272.95	$272.90
7 purchase totals =	$798.59		$875.0353	$875.04	$875.05	$875.00