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	$165.84	5.773%	$175.4139	$175.41	$175.40	$175.40
Purchase #2	$151.42	13.171%	$171.3635	$171.36	$171.35	$171.40
Purchase #3	$239.25	12.828%	$269.941	$269.94	$269.95	$269.90
Purchase #4	$196.71	13.584%	$223.4311	$223.43	$223.45	$223.40
Purchase #5	$127.37	11.744%	$142.3283	$142.33	$142.35	$142.30
Purchase #6	$221.48	5.408%	$233.4576	$233.46	$233.45	$233.50
Purchase #7	$227.82	8.277%	$246.6767	$246.68	$246.70	$246.70
7 purchase totals =	$1,329.89		$1,462.6121	$1,462.61	$1,462.65	$1,462.60