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 $70.49   7.750%   $75.953   $75.95   $75.95   $76.00  
  Purchase #2 $123.74   6.568%   $131.8672   $131.87   $131.85   $131.90  
  Purchase #3 $60.47   3.732%   $62.7267   $62.73   $62.75   $62.70  
  Purchase #4 $169.59   6.406%   $180.4539   $180.45   $180.45   $180.50  
  Purchase #5 $205.84   7.751%   $221.7947   $221.79   $221.80   $221.80  
  Purchase #6 $111.61   5.415%   $117.6537   $117.65   $117.65   $117.70  
  Purchase #7 $204.28   8.492%   $221.6275   $221.63   $221.65   $221.60  
  7 purchase totals = $946.02       $1,012.0767   $1,012.07   $1,012.10   $1,012.20