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	$174.92	11.371%	$194.8102	$194.81	$194.80	$194.80
Purchase #2	$102.97	9.701%	$112.9591	$112.96	$112.95	$113.00
Purchase #3	$232.62	13.119%	$263.1374	$263.14	$263.15	$263.10
Purchase #4	$123.97	3.394%	$128.1775	$128.18	$128.20	$128.20
Purchase #5	$95.42	4.139%	$99.3694	$99.37	$99.35	$99.40
Purchase #6	$159.72	8.688%	$173.5965	$173.60	$173.60	$173.60
Purchase #7	$102.84	6.809%	$109.8424	$109.84	$109.85	$109.80
7 purchase totals =	$992.46		$1,081.8925	$1,081.90	$1,081.90	$1,081.90