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	$189.90	10.871%	$210.544	$210.54	$210.55	$210.50
Purchase #2	$164.60	6.189%	$174.7871	$174.79	$174.80	$174.80
Purchase #3	$182.56	4.150%	$190.1362	$190.14	$190.15	$190.10
Purchase #4	$107.33	5.166%	$112.8747	$112.87	$112.85	$112.90
Purchase #5	$157.51	4.764%	$165.0138	$165.01	$165.00	$165.00
Purchase #6	$159.83	11.819%	$178.7203	$178.72	$178.70	$178.70
Purchase #7	$11.34	5.315%	$11.9427	$11.94	$11.95	$11.90
7 purchase totals =	$973.07		$1,044.0188	$1,044.01	$1,044.00	$1,043.90