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	$105.79	10.543%	$116.9434	$116.94	$116.95	$116.90
Purchase #2	$6.50	12.543%	$7.3153	$7.32	$7.30	$7.30
Purchase #3	$152.44	10.833%	$168.9538	$168.95	$168.95	$169.00
Purchase #4	$160.94	3.150%	$166.0096	$166.01	$166.00	$166.00
Purchase #5	$168.65	13.339%	$191.1462	$191.15	$191.15	$191.10
Purchase #6	$205.55	11.131%	$228.4298	$228.43	$228.45	$228.40
Purchase #7	$179.30	7.327%	$192.4373	$192.44	$192.45	$192.40
7 purchase totals =	$979.17		$1,071.2354	$1,071.24	$1,071.25	$1,071.10