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	$69.61	9.558%	$76.2633	$76.26	$76.25	$76.30
Purchase #2	$69.37	13.662%	$78.8473	$78.85	$78.85	$78.80
Purchase #3	$152.70	4.795%	$160.022	$160.02	$160.00	$160.00
Purchase #4	$94.52	6.718%	$100.8699	$100.87	$100.85	$100.90
Purchase #5	$109.56	12.668%	$123.4391	$123.44	$123.45	$123.40
Purchase #6	$136.88	5.103%	$143.865	$143.87	$143.85	$143.90
Purchase #7	$200.97	8.776%	$218.6071	$218.61	$218.60	$218.60
7 purchase totals =	$833.61		$901.9137	$901.92	$901.85	$901.90