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 $126.62   5.852%   $134.0298   $134.03   $134.05   $134.00  
  Purchase #2 $194.26   10.778%   $215.1973   $215.20   $215.20   $215.20  
  Purchase #3 $97.60   12.133%   $109.4418   $109.44   $109.45   $109.40  
  Purchase #4 $192.39   9.677%   $211.0076   $211.01   $211.00   $211.00  
  Purchase #5 $197.86   4.832%   $207.4206   $207.42   $207.40   $207.40  
  Purchase #6 $156.64   11.369%   $174.4484   $174.45   $174.45   $174.40  
  Purchase #7 $91.51   11.153%   $101.7161   $101.72   $101.70   $101.70  
  7 purchase totals = $1,056.88       $1,153.2616   $1,153.27   $1,153.25   $1,153.10