I do not recommend that you do a daily accrual for money market or bond funds. I have been processing plans in a daily environment since 1986 (ok, I'm really showing my age) and have never processed an interest accrual for bond or money market funds.
We recommend to the TPA firms for whom we providing consulting that they setup the money market or bond fund as a cash account that carries a value of 1. Then, when the interest is paid by the fund at the end of the period, typically monthly, the TPA would spread that interest to all participants in the plan on the date they are posting the transaction.
If a participant leaves in the middle of the month, so be it. They just do not receive their pro-rata portion of that month's interest amount. In all my years in providing daily services, I have never seen this been an issue with a participant.
Most of the recordkeeping systems are setup to handle the accrual. However, as suggested by Fredman, there can be a problem of having enough cash to fund the accrual. If you are acting in a non-fiduciary capacity, as most TPA firms are, you probably do not want to be the entity that "funds" the shortage. It will have to come from somewhere, typically the employer, since the custodian issuing the check will typically only issue an amount equal to the cash they have on hand.