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 $57.76   7.250%   $61.9476   $61.95   $61.95   $61.90  
  Purchase #2 $155.58   7.583%   $167.3776   $167.38   $167.40   $167.40  
  Purchase #3 $219.51   6.721%   $234.2633   $234.26   $234.25   $234.30  
  Purchase #4 $175.43   10.126%   $193.194   $193.19   $193.20   $193.20  
  Purchase #5 $105.80   5.609%   $111.7343   $111.73   $111.75   $111.70  
  Purchase #6 $45.91   13.286%   $52.0096   $52.01   $52.00   $52.00  
  Purchase #7 $97.78   7.571%   $105.1829   $105.18   $105.20   $105.20  
  7 purchase totals = $857.77       $925.7093   $925.70   $925.75   $925.70