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	$173.53	6.285%	$184.4364	$184.44	$184.45	$184.40
Purchase #2	$188.64	10.297%	$208.0643	$208.06	$208.05	$208.10
Purchase #3	$192.84	6.577%	$205.5231	$205.52	$205.50	$205.50
Purchase #4	$164.27	11.729%	$183.5372	$183.54	$183.55	$183.50
Purchase #5	$161.48	11.629%	$180.2585	$180.26	$180.25	$180.30
Purchase #6	$75.66	13.151%	$85.61	$85.61	$85.60	$85.60
Purchase #7	$49.30	10.449%	$54.4514	$54.45	$54.45	$54.50
7 purchase totals =	$1,005.72		$1,101.8809	$1,101.88	$1,101.85	$1,101.90