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	$174.91	4.316%	$182.4591	$182.46	$182.45	$182.50
Purchase #2	$38.48	5.266%	$40.5064	$40.51	$40.50	$40.50
Purchase #3	$11.35	4.396%	$11.8489	$11.85	$11.85	$11.80
Purchase #4	$249.38	3.559%	$258.2554	$258.26	$258.25	$258.30
Purchase #5	$59.65	4.357%	$62.249	$62.25	$62.25	$62.20
Purchase #6	$247.65	13.856%	$281.9644	$281.96	$281.95	$282.00
Purchase #7	$180.30	11.338%	$200.7424	$200.74	$200.75	$200.70
7 purchase totals =	$961.72		$1,038.0256	$1,038.03	$1,038.00	$1,038.00