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	$211.77	10.695%	$234.4188	$234.42	$234.40	$234.40
Purchase #2	$48.47	10.369%	$53.4959	$53.50	$53.50	$53.50
Purchase #3	$215.73	4.549%	$225.5436	$225.54	$225.55	$225.50
Purchase #4	$113.48	13.232%	$128.4957	$128.50	$128.50	$128.50
Purchase #5	$44.90	4.518%	$46.9286	$46.93	$46.95	$46.90
Purchase #6	$164.53	13.754%	$187.1595	$187.16	$187.15	$187.20
Purchase #7	$157.33	13.474%	$178.5286	$178.53	$178.55	$178.50
7 purchase totals =	$956.21		$1,054.5707	$1,054.58	$1,054.60	$1,054.50