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	$193.90	13.268%	$219.6267	$219.63	$219.65	$219.60
Purchase #2	$209.29	12.431%	$235.3068	$235.31	$235.30	$235.30
Purchase #3	$207.46	6.713%	$221.3868	$221.39	$221.40	$221.40
Purchase #4	$85.61	5.394%	$90.2278	$90.23	$90.25	$90.20
Purchase #5	$203.55	7.836%	$219.5002	$219.50	$219.50	$219.50
Purchase #6	$184.61	8.399%	$200.1154	$200.12	$200.10	$200.10
Purchase #7	$165.51	6.593%	$176.4221	$176.42	$176.40	$176.40
7 purchase totals =	$1,249.93		$1,362.5858	$1,362.60	$1,362.60	$1,362.50