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	$231.40	13.332%	$262.2502	$262.25	$262.25	$262.30
Purchase #2	$79.45	13.627%	$90.2767	$90.28	$90.30	$90.30
Purchase #3	$187.92	6.599%	$200.3208	$200.32	$200.30	$200.30
Purchase #4	$235.73	3.699%	$244.4497	$244.45	$244.45	$244.40
Purchase #5	$133.54	4.560%	$139.6294	$139.63	$139.65	$139.60
Purchase #6	$64.48	5.323%	$67.9123	$67.91	$67.90	$67.90
Purchase #7	$8.85	7.255%	$9.4921	$9.49	$9.50	$9.50
7 purchase totals =	$941.37		$1,014.3312	$1,014.33	$1,014.35	$1,014.30