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	$200.86	11.524%	$224.0071	$224.01	$224.00	$224.00
Purchase #2	$22.77	13.570%	$25.8599	$25.86	$25.85	$25.90
Purchase #3	$52.88	12.601%	$59.5434	$59.54	$59.55	$59.50
Purchase #4	$88.63	6.338%	$94.2474	$94.25	$94.25	$94.20
Purchase #5	$112.54	12.257%	$126.334	$126.33	$126.35	$126.30
Purchase #6	$234.61	10.310%	$258.7983	$258.80	$258.80	$258.80
Purchase #7	$201.75	12.868%	$227.7112	$227.71	$227.70	$227.70
7 purchase totals =	$914.04		$1,016.5013	$1,016.50	$1,016.50	$1,016.40