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	$205.27	4.380%	$214.2608	$214.26	$214.25	$214.30
Purchase #2	$113.67	11.785%	$127.066	$127.07	$127.05	$127.10
Purchase #3	$103.92	5.320%	$109.4485	$109.45	$109.45	$109.40
Purchase #4	$39.53	10.362%	$43.6261	$43.63	$43.65	$43.60
Purchase #5	$174.49	9.644%	$191.3178	$191.32	$191.30	$191.30
Purchase #6	$235.68	3.641%	$244.2611	$244.26	$244.25	$244.30
Purchase #7	$142.75	10.364%	$157.5446	$157.54	$157.55	$157.50
7 purchase totals =	$1,015.31		$1,087.5249	$1,087.53	$1,087.50	$1,087.50