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	$24.61	3.126%	$25.3793	$25.38	$25.40	$25.40
Purchase #2	$70.64	11.140%	$78.5093	$78.51	$78.50	$78.50
Purchase #3	$249.27	5.309%	$262.5037	$262.50	$262.50	$262.50
Purchase #4	$211.83	8.194%	$229.1874	$229.19	$229.20	$229.20
Purchase #5	$90.77	8.511%	$98.4954	$98.50	$98.50	$98.50
Purchase #6	$117.97	7.781%	$127.1492	$127.15	$127.15	$127.10
Purchase #7	$181.82	12.578%	$204.6893	$204.69	$204.70	$204.70
7 purchase totals =	$946.91		$1,025.9136	$1,025.92	$1,025.95	$1,025.90