Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
  Case Tag  
Price  
Sales  
Tax %  
Raw Total  
Incl. Sales Tax  
Rounded  
to Penny  
Rounded  
to Nickel  
Rounded  
to Dime  
  Purchase #1 $86.28   10.845%   $95.6371   $95.64   $95.65   $95.60  
  Purchase #2 $203.66   7.605%   $219.1483   $219.15   $219.15   $219.10  
  Purchase #3 $206.55   5.605%   $218.1271   $218.13   $218.15   $218.10  
  Purchase #4 $182.40   8.817%   $198.4822   $198.48   $198.50   $198.50  
  Purchase #5 $116.31   7.624%   $125.1775   $125.18   $125.20   $125.20  
  Purchase #6 $150.52   12.497%   $169.3305   $169.33   $169.35   $169.30  
  Purchase #7 $116.93   9.595%   $128.1494   $128.15   $128.15   $128.10  
  7 purchase totals = $1,062.65       $1,154.0521   $1,154.06   $1,154.15   $1,153.90