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	$40.91	7.655%	$44.0417	$44.04	$44.05	$44.00
Purchase #2	$244.77	10.130%	$269.5652	$269.57	$269.55	$269.60
Purchase #3	$147.51	10.198%	$162.5531	$162.55	$162.55	$162.60
Purchase #4	$165.67	11.471%	$184.674	$184.67	$184.65	$184.70
Purchase #5	$86.84	4.619%	$90.8511	$90.85	$90.85	$90.90
Purchase #6	$93.29	12.574%	$105.0203	$105.02	$105.00	$105.00
Purchase #7	$168.97	8.654%	$183.5927	$183.59	$183.60	$183.60
7 purchase totals =	$947.96		$1,040.2981	$1,040.29	$1,040.25	$1,040.40