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	$232.74	12.625%	$262.1234	$262.12	$262.10	$262.10
Purchase #2	$230.48	10.834%	$255.4502	$255.45	$255.45	$255.50
Purchase #3	$32.84	11.662%	$36.6698	$36.67	$36.65	$36.70
Purchase #4	$48.99	6.250%	$52.0519	$52.05	$52.05	$52.10
Purchase #5	$43.36	4.417%	$45.2752	$45.28	$45.30	$45.30
Purchase #6	$175.92	11.684%	$196.4745	$196.47	$196.45	$196.50
Purchase #7	$209.86	8.376%	$227.4379	$227.44	$227.45	$227.40
7 purchase totals =	$974.19		$1,075.4829	$1,075.48	$1,075.45	$1,075.60