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	$177.73	12.723%	$200.3426	$200.34	$200.35	$200.30
Purchase #2	$107.30	8.572%	$116.4978	$116.50	$116.50	$116.50
Purchase #3	$196.85	6.411%	$209.4701	$209.47	$209.45	$209.50
Purchase #4	$190.57	9.337%	$208.3635	$208.36	$208.35	$208.40
Purchase #5	$165.81	12.334%	$186.261	$186.26	$186.25	$186.30
Purchase #6	$35.93	4.329%	$37.4854	$37.49	$37.50	$37.50
Purchase #7	$143.51	7.603%	$154.4211	$154.42	$154.40	$154.40
7 purchase totals =	$1,017.70		$1,112.8415	$1,112.84	$1,112.80	$1,112.90