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 $186.25   4.671%   $194.9497   $194.95   $194.95   $194.90  
  Purchase #2 $200.56   6.355%   $213.3056   $213.31   $213.30   $213.30  
  Purchase #3 $34.44   10.270%   $37.977   $37.98   $38.00   $38.00  
  Purchase #4 $238.92   11.459%   $266.2978   $266.30   $266.30   $266.30  
  Purchase #5 $106.87   4.861%   $112.065   $112.07   $112.05   $112.10  
  Purchase #6 $192.92   5.254%   $203.056   $203.06   $203.05   $203.10  
  Purchase #7 $85.27   3.756%   $88.4727   $88.47   $88.45   $88.50  
  7 purchase totals = $1,045.23       $1,116.1238   $1,116.14   $1,116.10   $1,116.20