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	$146.51	5.541%	$154.6281	$154.63	$154.65	$154.60
Purchase #2	$248.30	3.473%	$256.9235	$256.92	$256.90	$256.90
Purchase #3	$171.89	9.140%	$187.6007	$187.60	$187.60	$187.60
Purchase #4	$138.76	7.479%	$149.1379	$149.14	$149.15	$149.10
Purchase #5	$115.76	13.709%	$131.6295	$131.63	$131.65	$131.60
Purchase #6	$129.89	9.490%	$142.2166	$142.22	$142.20	$142.20
Purchase #7	$42.82	5.859%	$45.3288	$45.33	$45.35	$45.30
7 purchase totals =	$993.93		$1,067.4651	$1,067.47	$1,067.50	$1,067.30