Nitin,
One way to achieve this is to add a javascript code extension to modify your unit price array values to make sure there are two decimal places.
Assuming the UDO variable is unit_price (adjust the code to the correct variable name if needed), add this as a javascript code extension. Scope it to all tags and place it above the e-commerce extension in the UI and these values will be mapped for all tags using e-commerce.
for (i=0; i < b['unit_price'].length; i++) {
b['unit_price'][i] = parseFloat( b['unit_price'][i] ).toFixed(2);
}