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	$200.30	5.744%	$211.8052	$211.81	$211.80	$211.80
Purchase #2	$73.60	13.109%	$83.2482	$83.25	$83.25	$83.20
Purchase #3	$159.67	6.362%	$169.8282	$169.83	$169.85	$169.80
Purchase #4	$37.54	8.868%	$40.869	$40.87	$40.85	$40.90
Purchase #5	$245.94	6.345%	$261.5449	$261.54	$261.55	$261.50
Purchase #6	$181.60	13.119%	$205.4241	$205.42	$205.40	$205.40
Purchase #7	$204.37	9.547%	$223.8812	$223.88	$223.90	$223.90
7 purchase totals =	$1,103.02		$1,196.6008	$1,196.60	$1,196.60	$1,196.50