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	$184.89	6.594%	$197.0816	$197.08	$197.10	$197.10
Purchase #2	$186.32	7.104%	$199.5562	$199.56	$199.55	$199.60
Purchase #3	$12.78	4.287%	$13.3279	$13.33	$13.35	$13.30
Purchase #4	$228.52	6.749%	$243.9428	$243.94	$243.95	$243.90
Purchase #5	$238.42	3.752%	$247.3655	$247.37	$247.35	$247.40
Purchase #6	$84.72	13.191%	$95.8954	$95.90	$95.90	$95.90
Purchase #7	$72.32	8.416%	$78.4065	$78.41	$78.40	$78.40
7 purchase totals =	$1,007.97		$1,075.5759	$1,075.59	$1,075.60	$1,075.60