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 $43.81   9.690%   $48.0552   $48.06   $48.05   $48.10  
  Purchase #2 $194.59   3.446%   $201.2956   $201.30   $201.30   $201.30  
  Purchase #3 $110.97   9.663%   $121.693   $121.69   $121.70   $121.70  
  Purchase #4 $208.29   9.234%   $227.5235   $227.52   $227.50   $227.50  
  Purchase #5 $220.28   3.433%   $227.8422   $227.84   $227.85   $227.80  
  Purchase #6 $202.59   10.809%   $224.488   $224.49   $224.50   $224.50  
  Purchase #7 $65.59   12.181%   $73.5795   $73.58   $73.60   $73.60  
  7 purchase totals = $1,046.12       $1,124.4770   $1,124.48   $1,124.50   $1,124.50