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	$182.42	8.184%	$197.3493	$197.35	$197.35	$197.30
Purchase #2	$97.50	3.536%	$100.9476	$100.95	$100.95	$100.90
Purchase #3	$60.91	7.354%	$65.3893	$65.39	$65.40	$65.40
Purchase #4	$101.90	10.111%	$112.2031	$112.20	$112.20	$112.20
Purchase #5	$190.33	4.237%	$198.3943	$198.39	$198.40	$198.40
Purchase #6	$52.41	4.384%	$54.7077	$54.71	$54.70	$54.70
Purchase #7	$114.52	7.535%	$123.1491	$123.15	$123.15	$123.10
7 purchase totals =	$799.99		$852.1404	$852.14	$852.15	$852.00