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	$86.76	7.615%	$93.3668	$93.37	$93.35	$93.40
Purchase #2	$62.86	5.841%	$66.5317	$66.53	$66.55	$66.50
Purchase #3	$179.63	3.479%	$185.8793	$185.88	$185.90	$185.90
Purchase #4	$248.49	13.631%	$282.3617	$282.36	$282.35	$282.40
Purchase #5	$241.92	8.184%	$261.7187	$261.72	$261.70	$261.70
Purchase #6	$142.40	11.129%	$158.2477	$158.25	$158.25	$158.20
Purchase #7	$53.68	3.131%	$55.3607	$55.36	$55.35	$55.40
7 purchase totals =	$1,015.74		$1,103.4666	$1,103.47	$1,103.45	$1,103.50