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	$136.40	4.575%	$142.6403	$142.64	$142.65	$142.60
Purchase #2	$229.61	4.159%	$239.1595	$239.16	$239.15	$239.20
Purchase #3	$54.31	8.214%	$58.771	$58.77	$58.75	$58.80
Purchase #4	$93.68	9.591%	$102.6648	$102.66	$102.65	$102.70
Purchase #5	$130.63	5.180%	$137.3966	$137.40	$137.40	$137.40
Purchase #6	$178.32	10.216%	$196.5372	$196.54	$196.55	$196.50
Purchase #7	$241.46	10.301%	$266.3328	$266.33	$266.35	$266.30
7 purchase totals =	$1,064.41		$1,143.5022	$1,143.50	$1,143.50	$1,143.50