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 $117.95   10.234%   $130.021   $130.02   $130.00   $130.00  
  Purchase #2 $235.91   13.441%   $267.6187   $267.62   $267.60   $267.60  
  Purchase #3 $143.99   6.621%   $153.5236   $153.52   $153.50   $153.50  
  Purchase #4 $148.77   5.327%   $156.695   $156.70   $156.70   $156.70  
  Purchase #5 $5.75   10.417%   $6.349   $6.35   $6.35   $6.30  
  Purchase #6 $151.86   12.121%   $170.267   $170.27   $170.25   $170.30  
  Purchase #7 $196.80   7.445%   $211.4518   $211.45   $211.45   $211.50  
  7 purchase totals = $1,001.03       $1,095.9261   $1,095.93   $1,095.85   $1,095.90