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	$219.28	4.720%	$229.63	$229.63	$229.65	$229.60
Purchase #2	$47.85	9.566%	$52.4273	$52.43	$52.45	$52.40
Purchase #3	$108.77	4.447%	$113.607	$113.61	$113.60	$113.60
Purchase #4	$175.60	3.180%	$181.1841	$181.18	$181.20	$181.20
Purchase #5	$159.61	5.520%	$168.4205	$168.42	$168.40	$168.40
Purchase #6	$101.89	12.293%	$114.4153	$114.42	$114.40	$114.40
Purchase #7	$219.98	5.132%	$231.2694	$231.27	$231.25	$231.30
7 purchase totals =	$1,032.98		$1,090.9536	$1,090.96	$1,090.95	$1,090.90