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	$103.41	10.672%	$114.4459	$114.45	$114.45	$114.40
Purchase #2	$98.49	11.658%	$109.972	$109.97	$109.95	$110.00
Purchase #3	$107.37	8.589%	$116.592	$116.59	$116.60	$116.60
Purchase #4	$86.54	13.659%	$98.3605	$98.36	$98.35	$98.40
Purchase #5	$212.60	5.423%	$224.1293	$224.13	$224.15	$224.10
Purchase #6	$118.68	8.126%	$128.3239	$128.32	$128.30	$128.30
Purchase #7	$238.93	12.685%	$269.2383	$269.24	$269.25	$269.20
7 purchase totals =	$966.02		$1,061.0619	$1,061.06	$1,061.05	$1,061.00