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	$113.51	11.819%	$126.9257	$126.93	$126.95	$126.90
Purchase #2	$90.25	11.258%	$100.4103	$100.41	$100.40	$100.40
Purchase #3	$185.67	12.168%	$208.2623	$208.26	$208.25	$208.30
Purchase #4	$121.78	4.516%	$127.2796	$127.28	$127.30	$127.30
Purchase #5	$248.26	9.337%	$271.44	$271.44	$271.45	$271.40
Purchase #6	$118.87	4.705%	$124.4628	$124.46	$124.45	$124.50
Purchase #7	$228.30	4.541%	$238.6671	$238.67	$238.65	$238.70
7 purchase totals =	$1,106.64		$1,197.4478	$1,197.45	$1,197.45	$1,197.50