The term 'Till Compartment' refers to the two sections of a cash register, the TENS and ONES compartments. The TENS compartment is used to store coins and bills of higher denominations, such as 10s, 20s, 50s, and 100s. The ONES compartment is used to store coins and bills of lower denominations, such as 1s, 5s, and 10s. Together, these two compartments make up the Till Compartment, which is an essential part of any cash register.