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	$41.94	4.557%	$43.8512	$43.85	$43.85	$43.90
Purchase #2	$116.83	9.190%	$127.5667	$127.57	$127.55	$127.60
Purchase #3	$163.82	3.386%	$169.3669	$169.37	$169.35	$169.40
Purchase #4	$63.70	11.518%	$71.037	$71.04	$71.05	$71.00
Purchase #5	$87.58	3.265%	$90.4395	$90.44	$90.45	$90.40
Purchase #6	$136.42	7.369%	$146.4728	$146.47	$146.45	$146.50
Purchase #7	$101.27	6.193%	$107.5417	$107.54	$107.55	$107.50
7 purchase totals =	$711.56		$756.2758	$756.28	$756.25	$756.30