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	$161.44	4.430%	$168.5918	$168.59	$168.60	$168.60
Purchase #2	$202.30	3.154%	$208.6805	$208.68	$208.70	$208.70
Purchase #3	$174.76	4.325%	$182.3184	$182.32	$182.30	$182.30
Purchase #4	$74.51	5.827%	$78.8517	$78.85	$78.85	$78.90
Purchase #5	$107.32	4.154%	$111.7781	$111.78	$111.80	$111.80
Purchase #6	$194.51	11.585%	$217.044	$217.04	$217.05	$217.00
Purchase #7	$161.36	3.848%	$167.5691	$167.57	$167.55	$167.60
7 purchase totals =	$1,076.20		$1,134.8336	$1,134.83	$1,134.85	$1,134.90