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 $86.98   9.199%   $94.9813   $94.98   $95.00   $95.00  
  Purchase #2 $229.80   3.584%   $238.036   $238.04   $238.05   $238.00  
  Purchase #3 $167.34   13.163%   $189.367   $189.37   $189.35   $189.40  
  Purchase #4 $155.68   13.158%   $176.1644   $176.16   $176.15   $176.20  
  Purchase #5 $119.31   7.214%   $127.917   $127.92   $127.90   $127.90  
  Purchase #6 $172.79   6.400%   $183.8486   $183.85   $183.85   $183.80  
  Purchase #7 $220.39   13.746%   $250.6848   $250.68   $250.70   $250.70  
  7 purchase totals = $1,152.29       $1,260.9991   $1,261.00   $1,261.00   $1,261.00