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	$163.53	5.813%	$173.036	$173.04	$173.05	$173.00
Purchase #2	$55.71	3.206%	$57.4961	$57.50	$57.50	$57.50
Purchase #3	$244.89	4.190%	$255.1509	$255.15	$255.15	$255.20
Purchase #4	$128.63	4.788%	$134.7888	$134.79	$134.80	$134.80
Purchase #5	$89.71	5.839%	$94.9482	$94.95	$94.95	$94.90
Purchase #6	$168.29	4.278%	$175.4894	$175.49	$175.50	$175.50
Purchase #7	$147.58	11.156%	$164.044	$164.04	$164.05	$164.00
7 purchase totals =	$998.34		$1,054.9534	$1,054.96	$1,055.00	$1,054.90