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	$191.71	11.830%	$214.3893	$214.39	$214.40	$214.40
Purchase #2	$161.28	11.260%	$179.4401	$179.44	$179.45	$179.40
Purchase #3	$52.26	3.615%	$54.1492	$54.15	$54.15	$54.10
Purchase #4	$121.98	4.281%	$127.202	$127.20	$127.20	$127.20
Purchase #5	$184.92	8.190%	$200.0649	$200.06	$200.05	$200.10
Purchase #6	$39.80	13.751%	$45.2729	$45.27	$45.25	$45.30
Purchase #7	$151.63	7.446%	$162.9204	$162.92	$162.90	$162.90
7 purchase totals =	$903.58		$983.4388	$983.43	$983.40	$983.40