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	$131.83	7.741%	$142.035	$142.04	$142.05	$142.00
Purchase #2	$20.46	7.667%	$22.0287	$22.03	$22.05	$22.00
Purchase #3	$116.47	7.225%	$124.885	$124.89	$124.90	$124.90
Purchase #4	$127.29	11.315%	$141.6929	$141.69	$141.70	$141.70
Purchase #5	$116.37	9.570%	$127.5066	$127.51	$127.50	$127.50
Purchase #6	$80.80	4.712%	$84.6073	$84.61	$84.60	$84.60
Purchase #7	$95.81	11.102%	$106.4468	$106.45	$106.45	$106.40
7 purchase totals =	$689.03		$749.2023	$749.22	$749.25	$749.10