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	$111.26	11.515%	$124.0716	$124.07	$124.05	$124.10
Purchase #2	$97.82	3.716%	$101.455	$101.46	$101.45	$101.50
Purchase #3	$168.51	10.181%	$185.666	$185.67	$185.65	$185.70
Purchase #4	$242.75	5.761%	$256.7348	$256.73	$256.75	$256.70
Purchase #5	$109.27	8.120%	$118.1427	$118.14	$118.15	$118.10
Purchase #6	$226.86	9.534%	$248.4888	$248.49	$248.50	$248.50
Purchase #7	$10.90	5.564%	$11.5065	$11.51	$11.50	$11.50
7 purchase totals =	$967.37		$1,046.0654	$1,046.07	$1,046.05	$1,046.10