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	$235.89	9.855%	$259.137	$259.14	$259.15	$259.10
Purchase #2	$43.64	11.297%	$48.57	$48.57	$48.55	$48.60
Purchase #3	$85.37	4.824%	$89.4882	$89.49	$89.50	$89.50
Purchase #4	$229.82	10.600%	$254.1809	$254.18	$254.20	$254.20
Purchase #5	$124.95	4.108%	$130.0829	$130.08	$130.10	$130.10
Purchase #6	$198.62	10.175%	$218.8296	$218.83	$218.85	$218.80
Purchase #7	$22.39	10.769%	$24.8012	$24.80	$24.80	$24.80
7 purchase totals =	$940.68		$1,025.0898	$1,025.09	$1,025.15	$1,025.10