Course Catalog / BMU 020 / Lesson 3 of 5

BMU 020

Halfway review

1. How do you find a unit price?

See the answer

Price divided by size.

2. How do you find 10 percent?

See the answer

Move the decimal one place left.

3. What is a sale price?

See the answer

The price minus the discount.

Why this matters

It is hard to know the total until the cashier tells you. A quick estimate helps you stay on budget and spot mistakes.

In this lesson you will round prices, keep a running total, and check your receipt.

Start with what you already do

You already round. When something costs $9.99, you think of it as $10.

Common belief: Store prices are always right, so I do not need to check.

What is actually true: Errors happen. NIST says a store fails a price check when more than 2 percent of the prices checked do not match what is charged.

Key words

estimate

A close guess you can work out fast.

round

Change a number to a close, easy number, like $4.89 to $5.

running total

A sum you add to each time you pick something up.

Round each price

Look at the cents. If they are 50 or more, round up to the next dollar. If they are less than 50, round down.

Add the rounded prices: 3 plus 4 plus 2 plus 7 plus 3 is about $19. The real total is $18.53. The estimate is close.

Keep a running total

Add each item as you put it in the cart. You can do it in your head or on your phone calculator. Some people write it on the shopping list. If tax applies where you live, add a little extra to your estimate.

Check the receipt

• Look for items you did not buy or items scanned twice.
• Compare sale items to the sale price on the sign.
• Check before you leave the store if you can.
• Ask the store to fix any error.

If the store will not fix it

NIST says to contact your state weights and measures office about an overcharge. Each state has one. They check that the price on the shelf is the price you pay. NIST also says the FTC covers most pricing practices, and every state has rules against wrong prices.

Text version of this figure

Estimate before you pay. Round, add, check.

1. Step 1, Round each price: 50 cents or more rounds up.
2. Step 2, Keep a running total: Add as you shop.
3. Step 3, Add a little for tax: If tax applies where you live.
4. Check the receipt: Doubles, wrong prices, missing sales.
5. Ask for a fix: Then your state weights and measures office.

Source: NIST Price Verification FAQs (Oct 29, 2026).

Worked example: Sam's grocery run

Sam has $25 for groceries.

• He rounds each item as he shops: $3, $4, $2, $7, and $3.
• His running total is about $19.
• He adds about $1 for tax on some items. He estimates about $20.
• At the register the total is $19.44. On the receipt he sees the soap rang up twice. He asks, and the cashier takes it off.

Sam is a made up example.

Practice: Estimate, then check

Round each price to the nearest dollar and add. Then check the receipt. All prices are made up.

1. Your cart: $1.99, $5.49, $3.50, and $0.89. About how much?
2. The receipt shows $3.50 two times, but you bought one. What do you do?
3. Your estimate is $12, but the total is $21. What do you do?

Check your practice: feedback

1. $2 + $5 + $4 + $1 is about $12. The real total is $11.87.
2. Ask the cashier to fix it before you leave. Point to the line.
3. Check each line. A big gap means a wrong price, a double scan, or a missed sale.

Common mistakes

• Rounding every price down. Round up when the cents are 50 or more.
• Leaving out tax. Add a little if tax applies.
• Leaving before checking the receipt. Check it at the store.

Check your understanding

Take it as many times as you like. Pick an answer, then open the feedback.

1. Round $5.79 to the nearest dollar.

1. $5
2. $6
3. $5.80

See the answer and feedback

B is correct. Yes. 79 cents is 50 or more, so round up.

A: 79 cents rounds up. Review Round each price.

C: That is to the nearest 10 cents. Review Round each price.

2. You round three prices to $3, $4, and $2. What is your estimate?

1. $9
2. $7
3. $12

See the answer and feedback

A is correct. Yes. 3 plus 4 plus 2 is 9.

B: Add all three. Review Round each price.

C: Check your adding. Review Round each price.

3. A store will not fix an overcharge. Who can you contact?

1. Your bank
2. The company that made the product
3. The state office that checks prices and scales

See the answer and feedback

C is correct. Yes. Your state weights and measures office.

A: Your bank cannot check store prices. Call your state weights and measures office. Review If the store will not fix it.

B: The maker does not set the store's price. Call your state weights and measures office. Review If the store will not fix it.

Next up

Next you will read a pay stub line by line. Go to Lesson 4: Your pay stub, line by line.

Key words: Course glossary (A to Z, with the lesson that teaches each one).

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