The Placeholder Slips.

Use these when your sinking funds reach an amount you wish to deposit $1,000 or $50 etc.  
Deposit the money in your account and place your $1,000 (or $500) bill in your envelope to give visual representation for the $1,000 (or $500) you now have in savings. 

NOTE: You will receive a variety of each:

$500, $1,000, $2,000, $3,000, $5,000, $10,000, and FULLY Funded Placeholders