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	$208.55	6.426%	$221.9514	$221.95	$221.95	$222.00
Purchase #2	$153.30	5.841%	$162.2543	$162.25	$162.25	$162.30
Purchase #3	$201.46	11.359%	$224.3438	$224.34	$224.35	$224.30
Purchase #4	$118.98	10.213%	$131.1314	$131.13	$131.15	$131.10
Purchase #5	$81.41	5.592%	$85.9624	$85.96	$85.95	$86.00
Purchase #6	$97.70	7.334%	$104.8653	$104.87	$104.85	$104.90
Purchase #7	$80.53	6.644%	$85.8804	$85.88	$85.90	$85.90
7 purchase totals =	$941.93		$1,016.3890	$1,016.38	$1,016.40	$1,016.50