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	$213.25	4.540%	$222.9316	$222.93	$222.95	$222.90
Purchase #2	$224.86	7.692%	$242.1562	$242.16	$242.15	$242.20
Purchase #3	$47.64	10.556%	$52.6689	$52.67	$52.65	$52.70
Purchase #4	$180.40	8.741%	$196.1688	$196.17	$196.15	$196.20
Purchase #5	$114.76	3.760%	$119.075	$119.08	$119.10	$119.10
Purchase #6	$117.48	3.560%	$121.6623	$121.66	$121.65	$121.70
Purchase #7	$90.30	13.214%	$102.2322	$102.23	$102.25	$102.20
7 purchase totals =	$988.69		$1,056.8950	$1,056.90	$1,056.90	$1,057.00