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 $182.28   6.433%   $194.0061   $194.01   $194.00   $194.00  
  Purchase #2 $10.35   7.459%   $11.122   $11.12   $11.10   $11.10  
  Purchase #3 $54.97   8.443%   $59.6111   $59.61   $59.60   $59.60  
  Purchase #4 $106.60   11.514%   $118.8739   $118.87   $118.85   $118.90  
  Purchase #5 $187.79   4.262%   $195.7936   $195.79   $195.80   $195.80  
  Purchase #6 $50.65   13.683%   $57.5804   $57.58   $57.60   $57.60  
  Purchase #7 $118.98   10.110%   $131.0089   $131.01   $131.00   $131.00  
  7 purchase totals = $711.62       $767.9960   $767.99   $767.95   $768.00