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	$201.82	3.203%	$208.2843	$208.28	$208.30	$208.30
Purchase #2	$39.87	10.155%	$43.9188	$43.92	$43.90	$43.90
Purchase #3	$158.25	10.625%	$175.0641	$175.06	$175.05	$175.10
Purchase #4	$229.31	3.327%	$236.9391	$236.94	$236.95	$236.90
Purchase #5	$58.97	10.276%	$65.0298	$65.03	$65.05	$65.00
Purchase #6	$190.45	4.691%	$199.384	$199.38	$199.40	$199.40
Purchase #7	$123.33	7.354%	$132.3997	$132.40	$132.40	$132.40
7 purchase totals =	$1,002.00		$1,061.0198	$1,061.01	$1,061.05	$1,061.00