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	$216.91	3.134%	$223.708	$223.71	$223.70	$223.70
Purchase #2	$170.47	9.152%	$186.0714	$186.07	$186.05	$186.10
Purchase #3	$51.66	8.743%	$56.1766	$56.18	$56.20	$56.20
Purchase #4	$133.55	12.423%	$150.1409	$150.14	$150.15	$150.10
Purchase #5	$207.94	3.123%	$214.434	$214.43	$214.45	$214.40
Purchase #6	$39.57	5.178%	$41.6189	$41.62	$41.60	$41.60
Purchase #7	$196.30	13.810%	$223.409	$223.41	$223.40	$223.40
7 purchase totals =	$1,016.40		$1,095.5588	$1,095.56	$1,095.55	$1,095.50