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	$94.93	13.552%	$107.7949	$107.79	$107.80	$107.80
Purchase #2	$160.73	13.128%	$181.8306	$181.83	$181.85	$181.80
Purchase #3	$145.76	3.530%	$150.9053	$150.91	$150.90	$150.90
Purchase #4	$182.92	7.632%	$196.8805	$196.88	$196.90	$196.90
Purchase #5	$127.38	4.391%	$132.9733	$132.97	$132.95	$133.00
Purchase #6	$99.27	4.292%	$103.5307	$103.53	$103.55	$103.50
Purchase #7	$220.54	3.293%	$227.8024	$227.80	$227.80	$227.80
7 purchase totals =	$1,031.53		$1,101.7177	$1,101.71	$1,101.75	$1,101.70