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	$211.41	10.724%	$234.0816	$234.08	$234.10	$234.10
Purchase #2	$220.35	4.224%	$229.6576	$229.66	$229.65	$229.70
Purchase #3	$228.76	11.331%	$254.6808	$254.68	$254.70	$254.70
Purchase #4	$112.39	13.645%	$127.7256	$127.73	$127.75	$127.70
Purchase #5	$118.73	3.682%	$123.1016	$123.10	$123.10	$123.10
Purchase #6	$144.90	5.281%	$152.5522	$152.55	$152.55	$152.60
Purchase #7	$136.41	11.483%	$152.074	$152.07	$152.05	$152.10
7 purchase totals =	$1,172.95		$1,273.8734	$1,273.87	$1,273.90	$1,274.00