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	$164.54	5.290%	$173.2442	$173.24	$173.25	$173.20
Purchase #2	$138.53	10.117%	$152.5451	$152.55	$152.55	$152.50
Purchase #3	$135.46	6.594%	$144.3922	$144.39	$144.40	$144.40
Purchase #4	$156.82	8.138%	$169.582	$169.58	$169.60	$169.60
Purchase #5	$174.78	7.710%	$188.2555	$188.26	$188.25	$188.30
Purchase #6	$189.94	11.377%	$211.5495	$211.55	$211.55	$211.50
Purchase #7	$10.30	12.276%	$11.5644	$11.56	$11.55	$11.60
7 purchase totals =	$970.37		$1,051.1329	$1,051.13	$1,051.15	$1,051.10