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	$100.30	11.694%	$112.0291	$112.03	$112.05	$112.00
Purchase #2	$196.47	4.119%	$204.5626	$204.56	$204.55	$204.60
Purchase #3	$123.49	12.772%	$139.2621	$139.26	$139.25	$139.30
Purchase #4	$219.26	3.803%	$227.5985	$227.60	$227.60	$227.60
Purchase #5	$75.61	9.307%	$82.647	$82.65	$82.65	$82.60
Purchase #6	$107.89	3.528%	$111.6964	$111.70	$111.70	$111.70
Purchase #7	$164.33	6.350%	$174.765	$174.77	$174.75	$174.80
7 purchase totals =	$987.35		$1,052.5607	$1,052.57	$1,052.55	$1,052.60