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	$53.99	9.828%	$59.2961	$59.30	$59.30	$59.30
Purchase #2	$114.26	3.415%	$118.162	$118.16	$118.15	$118.20
Purchase #3	$139.47	3.523%	$144.3835	$144.38	$144.40	$144.40
Purchase #4	$237.87	8.597%	$258.3197	$258.32	$258.30	$258.30
Purchase #5	$181.61	9.112%	$198.1583	$198.16	$198.15	$198.20
Purchase #6	$216.56	11.449%	$241.354	$241.35	$241.35	$241.40
Purchase #7	$118.43	5.776%	$125.2705	$125.27	$125.25	$125.30
7 purchase totals =	$1,062.19		$1,144.9441	$1,144.94	$1,144.90	$1,145.10