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 $118.63   5.736%   $125.4346   $125.43   $125.45   $125.40  
  Purchase #2 $38.52   13.220%   $43.6123   $43.61   $43.60   $43.60  
  Purchase #3 $104.70   8.244%   $113.3315   $113.33   $113.35   $113.30  
  Purchase #4 $190.86   12.553%   $214.8187   $214.82   $214.80   $214.80  
  Purchase #5 $167.78   5.363%   $176.778   $176.78   $176.80   $176.80  
  Purchase #6 $181.77   13.294%   $205.9345   $205.93   $205.95   $205.90  
  Purchase #7 $207.40   3.786%   $215.2522   $215.25   $215.25   $215.30  
  7 purchase totals = $1,009.66       $1,095.1618   $1,095.15   $1,095.20   $1,095.10