Calculate Retail Sale Amount

To calculate the retail sale amount (the amount that will go on the wall sticker) 

Take the amount the artist has stipulated they want, divide it by 10, then times that number by 3. Then add the final number to the amount the artist has stipulated. If over $100 then round UP to the nearest $5 or $10 amount.

Example

Artist says they want $225 for their painting
$225 divided by 10 = $22.50
$22.50 x 3 = $67.50
$225 + $67.50 = 292.50

rounded up that is $295