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	$237.62	10.270%	$262.0236	$262.02	$262.00	$262.00
Purchase #2	$78.80	13.265%	$89.2528	$89.25	$89.25	$89.30
Purchase #3	$194.80	8.850%	$212.0398	$212.04	$212.05	$212.00
Purchase #4	$119.31	3.113%	$123.0241	$123.02	$123.00	$123.00
Purchase #5	$54.72	8.764%	$59.5157	$59.52	$59.50	$59.50
Purchase #6	$245.75	5.268%	$258.6961	$258.70	$258.70	$258.70
Purchase #7	$233.47	11.426%	$260.1463	$260.15	$260.15	$260.10
7 purchase totals =	$1,164.47		$1,264.6984	$1,264.70	$1,264.65	$1,264.60