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	$196.35	8.668%	$213.3696	$213.37	$213.35	$213.40
Purchase #2	$179.73	4.380%	$187.6022	$187.60	$187.60	$187.60
Purchase #3	$163.99	4.476%	$171.3302	$171.33	$171.35	$171.30
Purchase #4	$86.48	4.644%	$90.4961	$90.50	$90.50	$90.50
Purchase #5	$55.88	13.363%	$63.3472	$63.35	$63.35	$63.30
Purchase #6	$124.46	6.283%	$132.2798	$132.28	$132.30	$132.30
Purchase #7	$226.50	5.221%	$238.3256	$238.33	$238.35	$238.30
7 purchase totals =	$1,033.39		$1,096.7507	$1,096.76	$1,096.80	$1,096.70