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	$73.67	7.181%	$78.9602	$78.96	$78.95	$79.00
Purchase #2	$208.31	6.725%	$222.3188	$222.32	$222.30	$222.30
Purchase #3	$89.92	4.695%	$94.1417	$94.14	$94.15	$94.10
Purchase #4	$91.99	9.120%	$100.3795	$100.38	$100.40	$100.40
Purchase #5	$136.72	6.330%	$145.3744	$145.37	$145.35	$145.40
Purchase #6	$225.87	4.761%	$236.6237	$236.62	$236.60	$236.60
Purchase #7	$82.75	7.839%	$89.2368	$89.24	$89.25	$89.20
7 purchase totals =	$909.23		$967.0351	$967.03	$967.00	$967.00