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	$132.59	12.556%	$149.238	$149.24	$149.25	$149.20
Purchase #2	$118.27	4.625%	$123.74	$123.74	$123.75	$123.70
Purchase #3	$80.53	8.574%	$87.4346	$87.43	$87.45	$87.40
Purchase #4	$99.74	11.808%	$111.5173	$111.52	$111.50	$111.50
Purchase #5	$162.75	3.305%	$168.1289	$168.13	$168.15	$168.10
Purchase #6	$136.88	7.765%	$147.5087	$147.51	$147.50	$147.50
Purchase #7	$221.66	7.142%	$237.491	$237.49	$237.50	$237.50
7 purchase totals =	$952.42		$1,025.0585	$1,025.06	$1,025.10	$1,024.90