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 $205.88   13.490%   $233.6532   $233.65   $233.65   $233.70  
  Purchase #2 $207.51   13.342%   $235.196   $235.20   $235.20   $235.20  
  Purchase #3 $53.73   13.577%   $61.0249   $61.02   $61.00   $61.00  
  Purchase #4 $116.86   4.219%   $121.7903   $121.79   $121.80   $121.80  
  Purchase #5 $130.75   3.521%   $135.3537   $135.35   $135.35   $135.40  
  Purchase #6 $107.67   12.155%   $120.7573   $120.76   $120.75   $120.80  
  Purchase #7 $153.70   5.300%   $161.8461   $161.85   $161.85   $161.80  
  7 purchase totals = $976.10       $1,069.6215   $1,069.62   $1,069.60   $1,069.70