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	$140.84	11.501%	$157.038	$157.04	$157.05	$157.00
Purchase #2	$10.40	5.212%	$10.942	$10.94	$10.95	$10.90
Purchase #3	$112.63	13.140%	$127.4296	$127.43	$127.45	$127.40
Purchase #4	$242.37	8.428%	$262.7969	$262.80	$262.80	$262.80
Purchase #5	$38.50	13.774%	$43.803	$43.80	$43.80	$43.80
Purchase #6	$222.58	11.663%	$248.5395	$248.54	$248.55	$248.50
Purchase #7	$204.50	7.212%	$219.2485	$219.25	$219.25	$219.20
7 purchase totals =	$971.82		$1,069.7975	$1,069.80	$1,069.85	$1,069.60