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	$43.58	4.829%	$45.6845	$45.68	$45.70	$45.70
Purchase #2	$178.28	11.844%	$199.3955	$199.40	$199.40	$199.40
Purchase #3	$223.79	4.308%	$233.4309	$233.43	$233.45	$233.40
Purchase #4	$148.31	10.788%	$164.3097	$164.31	$164.30	$164.30
Purchase #5	$49.90	11.180%	$55.4788	$55.48	$55.50	$55.50
Purchase #6	$113.58	13.591%	$129.0167	$129.02	$129.00	$129.00
Purchase #7	$203.76	11.619%	$227.4349	$227.43	$227.45	$227.40
7 purchase totals =	$961.20		$1,054.7510	$1,054.75	$1,054.80	$1,054.70