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	$169.36	3.384%	$175.0911	$175.09	$175.10	$175.10
Purchase #2	$33.80	10.337%	$37.2939	$37.29	$37.30	$37.30
Purchase #3	$29.32	6.139%	$31.12	$31.12	$31.10	$31.10
Purchase #4	$214.46	3.668%	$222.3264	$222.33	$222.35	$222.30
Purchase #5	$77.39	9.191%	$84.5029	$84.50	$84.50	$84.50
Purchase #6	$67.66	5.426%	$71.3312	$71.33	$71.35	$71.30
Purchase #7	$70.81	5.810%	$74.9241	$74.92	$74.90	$74.90
7 purchase totals =	$662.80		$696.5896	$696.58	$696.60	$696.50