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	$94.84	13.266%	$107.4215	$107.42	$107.40	$107.40
Purchase #2	$144.42	5.606%	$152.5162	$152.52	$152.50	$152.50
Purchase #3	$250.53	4.821%	$262.6081	$262.61	$262.60	$262.60
Purchase #4	$205.71	7.362%	$220.8544	$220.85	$220.85	$220.90
Purchase #5	$213.53	4.268%	$222.6435	$222.64	$222.65	$222.60
Purchase #6	$42.31	5.172%	$44.4983	$44.50	$44.50	$44.50
Purchase #7	$93.57	8.298%	$101.3344	$101.33	$101.35	$101.30
7 purchase totals =	$1,044.91		$1,111.8764	$1,111.87	$1,111.85	$1,111.80