public static void main(String[] args) {
    String currencyValues = "45,890.00,12,345.00,23,765.34,56,908.50";
    String regEx = "\.[0-9]{2}[,]";
    String[] results = currencyValues.split(regEx);
    //System.out.println(Arrays.toString(results));
    for(String res : results) {
        System.out.println(res);
    }
}

45,890 //removing the decimals as the reg ex is exclusive
12,345
23,765
56,908.50

String regEx = "(?<=\.[0-9]{2}),";

public static void main(String[] args) {
    String currencyValues = "45,890.00,12,345.00,23,765.34,56,908.50";
    String regEx = "(?<=\.[0-9]{2}),"; // Using the regex with the look-behind
    String[] results = currencyValues.split(regEx);
    for (String res : results) {
        System.out.println(res);
    }
}

45,890.00
12,345.00
23,765.34
56,908.50

String currencyValues = "45,890.00,12,345.00,23,765.34,56,908.50,55.00,345,432.00";
 Pattern pattern = Pattern.compile("(\d{1,3},)?\d{1,3}\.\d{2}");
 Matcher m = pattern.matcher(currencyValues);
 while (m.find()) {
    System.out.println(m.group());
 }

45,890.00
12,345.00
23,765.34
56,908.50
55.00
345,432.00