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	$176.34	9.476%	$193.05	$193.05	$193.05	$193.10
Purchase #2	$185.82	7.851%	$200.4087	$200.41	$200.40	$200.40
Purchase #3	$31.86	4.392%	$33.2593	$33.26	$33.25	$33.30
Purchase #4	$189.98	11.429%	$211.6928	$211.69	$211.70	$211.70
Purchase #5	$80.99	9.379%	$88.5861	$88.59	$88.60	$88.60
Purchase #6	$127.25	9.697%	$139.5894	$139.59	$139.60	$139.60
Purchase #7	$38.90	4.460%	$40.6349	$40.63	$40.65	$40.60
7 purchase totals =	$831.14		$907.2212	$907.22	$907.25	$907.30