print: wrong rounding with implicit conversion transactions

[simonmichael]

Since 1.21, hledger print preserves all decimal digits in amounts (#931) - except in implicit conversion transactions like the following, where the commodity display style causes it to round inappropriately:

commodity A 1000.

2023-01-01
    f       A1.5
    g       A1.5
    c      B-3

$ hledger print                                                                                                                                                                         
2023-01-01                                                                                                                                                                                  
    f             A 2                                                                                                                                                                       
    g             A 2                                                                                                                                                                       
    c             B-3