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	$156.51	11.565%	$174.6104	$174.61	$174.60	$174.60
Purchase #2	$176.33	13.280%	$199.7466	$199.75	$199.75	$199.70
Purchase #3	$248.64	3.325%	$256.9073	$256.91	$256.90	$256.90
Purchase #4	$102.82	6.835%	$109.8477	$109.85	$109.85	$109.80
Purchase #5	$38.66	4.534%	$40.4128	$40.41	$40.40	$40.40
Purchase #6	$164.33	9.252%	$179.5338	$179.53	$179.55	$179.50
Purchase #7	$157.81	5.823%	$166.9993	$167.00	$167.00	$167.00
7 purchase totals =	$1,045.10		$1,128.0579	$1,128.06	$1,128.05	$1,127.90