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	$179.83	9.236%	$196.4391	$196.44	$196.45	$196.40
Purchase #2	$158.70	5.592%	$167.5745	$167.57	$167.55	$167.60
Purchase #3	$12.67	4.529%	$13.2438	$13.24	$13.25	$13.20
Purchase #4	$127.86	8.375%	$138.5683	$138.57	$138.55	$138.60
Purchase #5	$133.36	11.388%	$148.547	$148.55	$148.55	$148.50
Purchase #6	$240.40	6.720%	$256.5549	$256.55	$256.55	$256.60
Purchase #7	$172.27	7.642%	$185.4349	$185.43	$185.45	$185.40
7 purchase totals =	$1,025.09		$1,106.3625	$1,106.35	$1,106.35	$1,106.30