when you say “the parish” told you this, do you mean the secretary, the person running the baptismal classes, another parishioner who is not on staff, something published in their bulleting, or the pastor? Sometimes the person answering the phone is less than knowledgeable and precise about language and will talk about fees and costs, rather than stipends or offering, out of ignorance or carelessness. I would definitely talk to the pastor about this one because whoever told you this needs to be corrected. The sacraments are free and there can never be a mandatory charge. There can be a fee for books and supplies for prep classes, for use of the church and/or hall as for a wedding, or something similar, but no sacramental fee.