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	$86.60	11.338%	$96.4187	$96.42	$96.40	$96.40
Purchase #2	$5.39	8.840%	$5.8665	$5.87	$5.85	$5.90
Purchase #3	$184.33	6.546%	$196.3962	$196.40	$196.40	$196.40
Purchase #4	$15.87	4.375%	$16.5643	$16.56	$16.55	$16.60
Purchase #5	$166.78	11.319%	$185.6578	$185.66	$185.65	$185.70
Purchase #6	$152.56	5.850%	$161.4848	$161.48	$161.50	$161.50
Purchase #7	$165.69	4.575%	$173.2703	$173.27	$173.25	$173.30
7 purchase totals =	$777.22		$835.6586	$835.66	$835.60	$835.80