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 $46.58   7.489%   $50.0684   $50.07   $50.05   $50.10  
  Purchase #2 $243.78   7.604%   $262.317   $262.32   $262.30   $262.30  
  Purchase #3 $98.66   6.239%   $104.8154   $104.82   $104.80   $104.80  
  Purchase #4 $204.52   4.384%   $213.4862   $213.49   $213.50   $213.50  
  Purchase #5 $176.47   11.812%   $197.3146   $197.31   $197.30   $197.30  
  Purchase #6 $96.69   6.172%   $102.6577   $102.66   $102.65   $102.70  
  Purchase #7 $155.34   6.167%   $164.9198   $164.92   $164.90   $164.90  
  7 purchase totals = $1,022.04       $1,095.5791   $1,095.59   $1,095.50   $1,095.60