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	$235.57	10.362%	$259.9798	$259.98	$260.00	$260.00
Purchase #2	$24.87	4.185%	$25.9108	$25.91	$25.90	$25.90
Purchase #3	$53.59	6.748%	$57.2063	$57.21	$57.20	$57.20
Purchase #4	$152.96	5.606%	$161.5349	$161.53	$161.55	$161.50
Purchase #5	$164.55	10.296%	$181.4921	$181.49	$181.50	$181.50
Purchase #6	$103.90	5.603%	$109.7215	$109.72	$109.70	$109.70
Purchase #7	$238.98	7.345%	$256.5331	$256.53	$256.55	$256.50
7 purchase totals =	$974.42		$1,052.3785	$1,052.37	$1,052.40	$1,052.30