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	$46.65	12.763%	$52.6039	$52.60	$52.60	$52.60
Purchase #2	$176.46	3.507%	$182.6485	$182.65	$182.65	$182.60
Purchase #3	$36.44	3.333%	$37.6545	$37.65	$37.65	$37.70
Purchase #4	$99.46	12.597%	$111.989	$111.99	$112.00	$112.00
Purchase #5	$107.65	3.369%	$111.2767	$111.28	$111.30	$111.30
Purchase #6	$213.30	8.797%	$232.064	$232.06	$232.05	$232.10
Purchase #7	$65.83	3.826%	$68.3487	$68.35	$68.35	$68.30
7 purchase totals =	$745.79		$796.5853	$796.58	$796.60	$796.60