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 $60.54   3.788%   $62.8333   $62.83   $62.85   $62.80  
  Purchase #2 $141.64   5.317%   $149.171   $149.17   $149.15   $149.20  
  Purchase #3 $219.41   11.672%   $245.0195   $245.02   $245.00   $245.00  
  Purchase #4 $209.42   5.736%   $221.4323   $221.43   $221.45   $221.40  
  Purchase #5 $213.44   7.328%   $229.0809   $229.08   $229.10   $229.10  
  Purchase #6 $60.37   3.186%   $62.2934   $62.29   $62.30   $62.30  
  Purchase #7 $139.46   11.577%   $155.6053   $155.61   $155.60   $155.60  
  7 purchase totals = $1,044.28       $1,125.4357   $1,125.43   $1,125.45   $1,125.40