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	$64.72	12.588%	$72.867	$72.87	$72.85	$72.90
Purchase #2	$26.52	4.540%	$27.724	$27.72	$27.70	$27.70
Purchase #3	$205.74	9.535%	$225.3573	$225.36	$225.35	$225.40
Purchase #4	$196.54	9.130%	$214.4841	$214.48	$214.50	$214.50
Purchase #5	$142.42	6.495%	$151.6702	$151.67	$151.65	$151.70
Purchase #6	$37.33	10.662%	$41.3101	$41.31	$41.30	$41.30
Purchase #7	$192.44	13.857%	$219.1064	$219.11	$219.10	$219.10
7 purchase totals =	$865.71		$952.5191	$952.52	$952.45	$952.60