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	$101.88	3.610%	$105.5579	$105.56	$105.55	$105.60
Purchase #2	$215.81	11.714%	$241.09	$241.09	$241.10	$241.10
Purchase #3	$147.88	3.150%	$152.5382	$152.54	$152.55	$152.50
Purchase #4	$133.65	3.670%	$138.555	$138.56	$138.55	$138.60
Purchase #5	$197.56	13.130%	$223.4996	$223.50	$223.50	$223.50
Purchase #6	$126.77	13.403%	$143.761	$143.76	$143.75	$143.80
Purchase #7	$150.69	8.119%	$162.9245	$162.92	$162.90	$162.90
7 purchase totals =	$1,074.24		$1,167.9262	$1,167.93	$1,167.90	$1,168.00