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	$135.61	4.298%	$141.4385	$141.44	$141.45	$141.40
Purchase #2	$117.90	7.697%	$126.9748	$126.97	$126.95	$127.00
Purchase #3	$161.87	3.593%	$167.686	$167.69	$167.70	$167.70
Purchase #4	$97.78	13.620%	$111.0976	$111.10	$111.10	$111.10
Purchase #5	$167.65	5.702%	$177.2094	$177.21	$177.20	$177.20
Purchase #6	$131.96	11.622%	$147.2964	$147.30	$147.30	$147.30
Purchase #7	$205.58	11.113%	$228.4261	$228.43	$228.45	$228.40
7 purchase totals =	$1,018.35		$1,100.1288	$1,100.14	$1,100.15	$1,100.10