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 $176.83   10.371%   $195.169   $195.17   $195.15   $195.20  
  Purchase #2 $174.43   7.580%   $187.6518   $187.65   $187.65   $187.70  
  Purchase #3 $172.56   13.870%   $196.4941   $196.49   $196.50   $196.50  
  Purchase #4 $155.83   13.168%   $176.3497   $176.35   $176.35   $176.30  
  Purchase #5 $92.73   4.134%   $96.5635   $96.56   $96.55   $96.60  
  Purchase #6 $216.78   12.263%   $243.3637   $243.36   $243.35   $243.40  
  Purchase #7 $239.68   9.740%   $263.0248   $263.02   $263.00   $263.00  
  7 purchase totals = $1,228.84       $1,358.6166   $1,358.60   $1,358.55   $1,358.70