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	$97.59	11.741%	$109.048	$109.05	$109.05	$109.00
Purchase #2	$39.37	11.582%	$43.9298	$43.93	$43.95	$43.90
Purchase #3	$78.73	11.264%	$87.5981	$87.60	$87.60	$87.60
Purchase #4	$181.75	4.452%	$189.8415	$189.84	$189.85	$189.80
Purchase #5	$214.29	8.182%	$231.8232	$231.82	$231.80	$231.80
Purchase #6	$231.31	13.651%	$262.8861	$262.89	$262.90	$262.90
Purchase #7	$144.92	6.444%	$154.2586	$154.26	$154.25	$154.30
7 purchase totals =	$987.96		$1,079.3853	$1,079.39	$1,079.40	$1,079.30