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	$48.98	10.497%	$54.1214	$54.12	$54.10	$54.10
Purchase #2	$36.84	7.329%	$39.54	$39.54	$39.55	$39.50
Purchase #3	$232.48	6.647%	$247.9329	$247.93	$247.95	$247.90
Purchase #4	$167.48	8.161%	$181.148	$181.15	$181.15	$181.10
Purchase #5	$145.62	6.150%	$154.5756	$154.58	$154.60	$154.60
Purchase #6	$242.25	6.683%	$258.4396	$258.44	$258.45	$258.40
Purchase #7	$80.60	11.615%	$89.9617	$89.96	$89.95	$90.00
7 purchase totals =	$954.25		$1,025.7192	$1,025.72	$1,025.75	$1,025.60