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	$190.65	4.566%	$199.3551	$199.36	$199.35	$199.40
Purchase #2	$176.85	10.484%	$195.391	$195.39	$195.40	$195.40
Purchase #3	$117.94	8.199%	$127.6099	$127.61	$127.60	$127.60
Purchase #4	$72.87	8.153%	$78.8111	$78.81	$78.80	$78.80
Purchase #5	$132.49	3.337%	$136.9112	$136.91	$136.90	$136.90
Purchase #6	$130.92	12.540%	$147.3374	$147.34	$147.35	$147.30
Purchase #7	$249.30	5.121%	$262.0667	$262.07	$262.05	$262.10
7 purchase totals =	$1,071.02		$1,147.4824	$1,147.49	$1,147.45	$1,147.50