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 $183.33   6.384%   $195.0338   $195.03   $195.05   $195.00  
  Purchase #2 $55.96   8.428%   $60.6763   $60.68   $60.70   $60.70  
  Purchase #3 $120.51   4.270%   $125.6558   $125.66   $125.65   $125.70  
  Purchase #4 $247.91   6.114%   $263.0672   $263.07   $263.05   $263.10  
  Purchase #5 $172.54   4.158%   $179.7142   $179.71   $179.70   $179.70  
  Purchase #6 $121.77   12.489%   $136.9779   $136.98   $137.00   $137.00  
  Purchase #7 $155.29   6.448%   $165.3031   $165.30   $165.30   $165.30  
  7 purchase totals = $1,057.31       $1,126.4283   $1,126.43   $1,126.45   $1,126.50