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	$178.30	10.678%	$197.3389	$197.34	$197.35	$197.30
Purchase #2	$154.96	4.674%	$162.2028	$162.20	$162.20	$162.20
Purchase #3	$234.93	4.523%	$245.5559	$245.56	$245.55	$245.60
Purchase #4	$53.65	10.582%	$59.3272	$59.33	$59.35	$59.30
Purchase #5	$12.27	11.682%	$13.7034	$13.70	$13.70	$13.70
Purchase #6	$120.98	5.259%	$127.3423	$127.34	$127.35	$127.30
Purchase #7	$208.83	3.483%	$216.1035	$216.10	$216.10	$216.10
7 purchase totals =	$963.92		$1,021.5740	$1,021.57	$1,021.60	$1,021.50