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	$98.85	12.662%	$111.3664	$111.37	$111.35	$111.40
Purchase #2	$175.25	12.213%	$196.6533	$196.65	$196.65	$196.70
Purchase #3	$192.56	4.376%	$200.9864	$200.99	$201.00	$201.00
Purchase #4	$124.90	11.168%	$138.8488	$138.85	$138.85	$138.80
Purchase #5	$146.42	6.344%	$155.7089	$155.71	$155.70	$155.70
Purchase #6	$137.84	5.474%	$145.3854	$145.39	$145.40	$145.40
Purchase #7	$141.61	10.440%	$156.3941	$156.39	$156.40	$156.40
7 purchase totals =	$1,017.43		$1,105.3433	$1,105.35	$1,105.35	$1,105.40