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	$53.94	3.805%	$55.9924	$55.99	$56.00	$56.00
Purchase #2	$118.82	11.540%	$132.5318	$132.53	$132.55	$132.50
Purchase #3	$142.91	8.192%	$154.6172	$154.62	$154.60	$154.60
Purchase #4	$86.92	5.589%	$91.778	$91.78	$91.80	$91.80
Purchase #5	$224.92	10.545%	$248.6378	$248.64	$248.65	$248.60
Purchase #6	$73.45	7.478%	$78.9426	$78.94	$78.95	$78.90
Purchase #7	$245.79	6.783%	$262.4619	$262.46	$262.45	$262.50
7 purchase totals =	$946.75		$1,024.9617	$1,024.96	$1,025.00	$1,024.90