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	$62.28	10.308%	$68.6998	$68.70	$68.70	$68.70
Purchase #2	$159.45	13.845%	$181.5259	$181.53	$181.55	$181.50
Purchase #3	$127.77	4.218%	$133.1593	$133.16	$133.15	$133.20
Purchase #4	$139.98	3.538%	$144.9325	$144.93	$144.95	$144.90
Purchase #5	$176.90	7.450%	$190.0791	$190.08	$190.10	$190.10
Purchase #6	$172.83	13.721%	$196.544	$196.54	$196.55	$196.50
Purchase #7	$157.46	8.834%	$171.37	$171.37	$171.35	$171.40
7 purchase totals =	$996.67		$1,086.3106	$1,086.31	$1,086.35	$1,086.30