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	$182.27	5.162%	$191.6788	$191.68	$191.70	$191.70
Purchase #2	$172.67	10.555%	$190.8953	$190.90	$190.90	$190.90
Purchase #3	$168.86	10.477%	$186.5515	$186.55	$186.55	$186.60
Purchase #4	$185.58	3.539%	$192.1477	$192.15	$192.15	$192.10
Purchase #5	$134.83	6.291%	$143.3122	$143.31	$143.30	$143.30
Purchase #6	$42.30	7.434%	$45.4446	$45.44	$45.45	$45.40
Purchase #7	$69.63	4.589%	$72.8253	$72.83	$72.85	$72.80
7 purchase totals =	$956.14		$1,022.8554	$1,022.86	$1,022.90	$1,022.80