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	$152.50	7.707%	$164.2532	$164.25	$164.25	$164.30
Purchase #2	$66.37	7.382%	$71.2694	$71.27	$71.25	$71.30
Purchase #3	$9.90	7.168%	$10.6096	$10.61	$10.60	$10.60
Purchase #4	$52.84	7.726%	$56.9224	$56.92	$56.90	$56.90
Purchase #5	$170.52	5.647%	$180.1493	$180.15	$180.15	$180.10
Purchase #6	$33.32	9.408%	$36.4547	$36.45	$36.45	$36.50
Purchase #7	$202.40	11.510%	$225.6962	$225.70	$225.70	$225.70
7 purchase totals =	$687.85		$745.3548	$745.35	$745.30	$745.40