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 $183.61   6.717%   $195.9431   $195.94   $195.95   $195.90  
  Purchase #2 $29.64   5.338%   $31.2222   $31.22   $31.20   $31.20  
  Purchase #3 $50.36   6.330%   $53.5478   $53.55   $53.55   $53.50  
  Purchase #4 $206.32   11.856%   $230.7813   $230.78   $230.80   $230.80  
  Purchase #5 $135.78   11.485%   $151.3743   $151.37   $151.35   $151.40  
  Purchase #6 $228.31   5.330%   $240.4789   $240.48   $240.50   $240.50  
  Purchase #7 $141.64   5.670%   $149.671   $149.67   $149.65   $149.70  
  7 purchase totals = $975.66       $1,053.0186   $1,053.01   $1,053.00   $1,053.00