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	$179.65	12.381%	$201.8925	$201.89	$201.90	$201.90
Purchase #2	$127.33	3.217%	$131.4262	$131.43	$131.45	$131.40
Purchase #3	$69.89	10.772%	$77.4186	$77.42	$77.40	$77.40
Purchase #4	$199.91	5.801%	$211.5068	$211.51	$211.50	$211.50
Purchase #5	$194.46	13.812%	$221.3188	$221.32	$221.30	$221.30
Purchase #6	$61.71	9.543%	$67.599	$67.60	$67.60	$67.60
Purchase #7	$174.64	13.150%	$197.6052	$197.61	$197.60	$197.60
7 purchase totals =	$1,007.59		$1,108.7671	$1,108.78	$1,108.75	$1,108.70