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 $87.80   8.175%   $94.9777   $94.98   $95.00   $95.00  
  Purchase #2 $207.27   3.117%   $213.7306   $213.73   $213.75   $213.70  
  Purchase #3 $194.67   12.693%   $219.3795   $219.38   $219.40   $219.40  
  Purchase #4 $66.70   11.446%   $74.3345   $74.33   $74.35   $74.30  
  Purchase #5 $160.35   8.584%   $174.1144   $174.11   $174.10   $174.10  
  Purchase #6 $45.91   11.160%   $51.0336   $51.03   $51.05   $51.00  
  Purchase #7 $235.86   13.400%   $267.4652   $267.47   $267.45   $267.50  
  7 purchase totals = $998.56       $1,095.0355   $1,095.03   $1,095.10   $1,095.00