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 $174.60   6.614%   $186.148   $186.15   $186.15   $186.10  
  Purchase #2 $229.29   6.295%   $243.7238   $243.72   $243.70   $243.70  
  Purchase #3 $10.62   11.430%   $11.8339   $11.83   $11.85   $11.80  
  Purchase #4 $56.86   6.567%   $60.594   $60.59   $60.60   $60.60  
  Purchase #5 $247.45   5.343%   $260.6713   $260.67   $260.65   $260.70  
  Purchase #6 $155.65   8.110%   $168.2732   $168.27   $168.25   $168.30  
  Purchase #7 $175.40   4.246%   $182.8475   $182.85   $182.85   $182.80  
  7 purchase totals = $1,049.87       $1,114.0917   $1,114.08   $1,114.05   $1,114.00