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 $92.36   3.331%   $95.4365   $95.44   $95.45   $95.40  
  Purchase #2 $179.57   9.562%   $196.7405   $196.74   $196.75   $196.70  
  Purchase #3 $33.36   12.295%   $37.4616   $37.46   $37.45   $37.50  
  Purchase #4 $175.47   6.278%   $186.486   $186.49   $186.50   $186.50  
  Purchase #5 $188.26   3.150%   $194.1902   $194.19   $194.20   $194.20  
  Purchase #6 $196.84   6.320%   $209.2803   $209.28   $209.30   $209.30  
  Purchase #7 $184.36   13.519%   $209.2836   $209.28   $209.30   $209.30  
  7 purchase totals = $1,050.22       $1,128.8787   $1,128.88   $1,128.95   $1,128.90