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 $92.53   4.830%   $96.9992   $97.00   $97.00   $97.00  
  Purchase #2 $202.46   8.480%   $219.6286   $219.63   $219.65   $219.60  
  Purchase #3 $154.79   10.125%   $170.4625   $170.46   $170.45   $170.50  
  Purchase #4 $101.58   5.115%   $106.7758   $106.78   $106.80   $106.80  
  Purchase #5 $138.42   13.751%   $157.4541   $157.45   $157.45   $157.50  
  Purchase #6 $219.84   9.783%   $241.3469   $241.35   $241.35   $241.30  
  Purchase #7 $22.44   8.127%   $24.2637   $24.26   $24.25   $24.30  
  7 purchase totals = $932.06       $1,016.9308   $1,016.93   $1,016.95   $1,017.00