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	$209.58	8.504%	$227.4027	$227.40	$227.40	$227.40
Purchase #2	$122.93	8.680%	$133.6003	$133.60	$133.60	$133.60
Purchase #3	$146.69	4.156%	$152.7864	$152.79	$152.80	$152.80
Purchase #4	$177.79	5.352%	$187.3053	$187.31	$187.30	$187.30
Purchase #5	$98.38	13.721%	$111.8787	$111.88	$111.90	$111.90
Purchase #6	$88.72	13.273%	$100.4958	$100.50	$100.50	$100.50
Purchase #7	$176.63	11.574%	$197.0732	$197.07	$197.05	$197.10
7 purchase totals =	$1,020.72		$1,110.5424	$1,110.55	$1,110.55	$1,110.60