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	$186.85	3.748%	$193.8531	$193.85	$193.85	$193.90
Purchase #2	$63.99	13.165%	$72.4143	$72.41	$72.40	$72.40
Purchase #3	$68.54	8.798%	$74.5701	$74.57	$74.55	$74.60
Purchase #4	$36.31	3.668%	$37.6419	$37.64	$37.65	$37.60
Purchase #5	$126.75	12.429%	$142.5038	$142.50	$142.50	$142.50
Purchase #6	$135.88	6.276%	$144.4078	$144.41	$144.40	$144.40
Purchase #7	$172.94	13.727%	$196.6795	$196.68	$196.70	$196.70
7 purchase totals =	$791.26		$862.0705	$862.06	$862.05	$862.10