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	$120.72	4.738%	$126.4397	$126.44	$126.45	$126.40
Purchase #2	$184.95	6.212%	$196.4391	$196.44	$196.45	$196.40
Purchase #3	$12.85	4.809%	$13.468	$13.47	$13.45	$13.50
Purchase #4	$218.55	3.441%	$226.0703	$226.07	$226.05	$226.10
Purchase #5	$154.60	8.339%	$167.4921	$167.49	$167.50	$167.50
Purchase #6	$250.31	6.793%	$267.3136	$267.31	$267.30	$267.30
Purchase #7	$69.52	11.449%	$77.4793	$77.48	$77.50	$77.50
7 purchase totals =	$1,011.50		$1,074.7021	$1,074.70	$1,074.70	$1,074.70