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	$197.46	9.298%	$215.8198	$215.82	$215.80	$215.80
Purchase #2	$69.84	4.226%	$72.7914	$72.79	$72.80	$72.80
Purchase #3	$19.51	9.135%	$21.2922	$21.29	$21.30	$21.30
Purchase #4	$21.54	6.315%	$22.9003	$22.90	$22.90	$22.90
Purchase #5	$60.90	10.620%	$67.3676	$67.37	$67.35	$67.40
Purchase #6	$179.53	3.407%	$185.6466	$185.65	$185.65	$185.60
Purchase #7	$78.73	11.355%	$87.6698	$87.67	$87.65	$87.70
7 purchase totals =	$627.51		$673.4877	$673.49	$673.45	$673.50