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	$107.66	11.197%	$119.7147	$119.71	$119.70	$119.70
Purchase #2	$250.82	3.122%	$258.6506	$258.65	$258.65	$258.70
Purchase #3	$81.42	5.501%	$85.8989	$85.90	$85.90	$85.90
Purchase #4	$84.77	6.241%	$90.0605	$90.06	$90.05	$90.10
Purchase #5	$202.84	3.432%	$209.8015	$209.80	$209.80	$209.80
Purchase #6	$48.46	12.861%	$54.6924	$54.69	$54.70	$54.70
Purchase #7	$226.35	13.118%	$256.0426	$256.04	$256.05	$256.00
7 purchase totals =	$1,002.32		$1,074.8612	$1,074.85	$1,074.85	$1,074.90