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 $59.36   4.431%   $61.9902   $61.99   $62.00   $62.00  
  Purchase #2 $68.72   12.505%   $77.3134   $77.31   $77.30   $77.30  
  Purchase #3 $240.58   11.700%   $268.7279   $268.73   $268.75   $268.70  
  Purchase #4 $230.31   5.702%   $243.4423   $243.44   $243.45   $243.40  
  Purchase #5 $245.60   5.703%   $259.6066   $259.61   $259.60   $259.60  
  Purchase #6 $186.98   5.488%   $197.2415   $197.24   $197.25   $197.20  
  Purchase #7 $26.70   6.232%   $28.3639   $28.36   $28.35   $28.40  
  7 purchase totals = $1,058.25       $1,136.6858   $1,136.68   $1,136.70   $1,136.60