In Rentman, financial accuracy is essential, and the system always calculates using precise values in the background. However, since financial documents (like invoices) must be shown in whole cents, you may sometimes notice amounts that do not appear to add up exactly.

This article explains why these rounding differences occur, shows some examples, and clarifies how Rentman handles them.

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Common rounding scenarios

Scenario 1: Splitting an invoice

If an invoice total is split into equal parts, rounding can cause apparent mismatches. For example, if an invoice of $10.91 is split into two invoices, each half is $5.455.

Since values must be displayed in cents, both halves round to $5.46, creating a 1-cent difference.

Scenario 2: Unit price vs. Total price

Odd-looking prices often come from discounts, surcharges, or tiered pricing. For example:

1. You set an equipment item at 12.50 per unit.
2. You apply a 3% discount, so the real price becomes 12.125.
3. Rentman rounds this for display as 12.13.

If you rent 10 units, the total will look like:

item name        | unit price | amount | price 
-----------------+------------+--------+------- 
Table decoration | 12.13      | 10     | 121.25 

But in the background, Rentman is multiplying the exact price

12.125 × 10 = 121.25

Which is why the total and the displayed “rounded” unit price can look slightly mismatched.

The same thing can happen with larger totals. Suppose an item costs 100.00, and after a discount, Rentman calculates it as 100.246. Rentman shows 100.25:

100 x 100.25 = 10,025.00

But calculates the total based on the exact backend value:

100 x 100.246 = 10,024.60

This leads to a small difference between the displayed unit price and the calculated total.

Scenario 3: Group totals vs. Overall totals

In a project or invoice with multiple equipment groups, the group subtotals may not exactly match the displayed overall total.

Audio equipment = 1833.56 
Lighting equipment = 3863.12 
-----------------------------
Total equipment = 5696.67 

Here, the displayed total is 5696.67, which differs by a cent from the sum of the subtotals (5696.68).

Scenario 4: Totals with tax

The same can happen with tax calculations.

Total before tax = 5642.70 
VAT 21%                    1184.97 
------------------------
Total due = 6827.66 

The tax and subtotal amounts may not perfectly add up to the displayed total due to rounding at the cent level.

Why does this happen?

Rentman calculates all amounts with high precision in the background. For example, 5642.70 might actually be 5642.695.

Since financial documents must show values rounded to cents, each displayed number is rounded individually. When totals and subtotals round differently, the result can be a 1- or 2-cent difference.

Can Rentman prevent this?

Not completely. Rentman has to choose when to round:

• Rounding at each step would accumulate larger differences over time.
• Rounding only at the end ensures calculations are accurate, but may cause small mismatches between displayed values and totals.

Because of this trade-off, minor rounding differences are unavoidable.

What about accounting?

These rounding mismatches are normal in financial systems. Accounting software is designed to handle them by automatically posting small differences (usually 1–2 cents) into a special bookkeeping account, such as 'Rounding differences'. This ensures your books remain accurate even when invoice lines do not appear to add up perfectly.