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	$120.66	5.222%	$126.9609	$126.96	$126.95	$127.00
Purchase #2	$167.99	9.766%	$184.3959	$184.40	$184.40	$184.40
Purchase #3	$48.42	13.169%	$54.7964	$54.80	$54.80	$54.80
Purchase #4	$160.35	12.782%	$180.8459	$180.85	$180.85	$180.80
Purchase #5	$81.42	10.651%	$90.092	$90.09	$90.10	$90.10
Purchase #6	$178.89	3.664%	$185.4445	$185.44	$185.45	$185.40
Purchase #7	$202.70	13.712%	$230.4942	$230.49	$230.50	$230.50
7 purchase totals =	$960.43		$1,053.0298	$1,053.03	$1,053.05	$1,053.00