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	$98.33	13.241%	$111.3499	$111.35	$111.35	$111.30
Purchase #2	$166.62	11.681%	$186.0829	$186.08	$186.10	$186.10
Purchase #3	$150.86	9.459%	$165.1298	$165.13	$165.15	$165.10
Purchase #4	$84.25	6.670%	$89.8695	$89.87	$89.85	$89.90
Purchase #5	$248.27	3.397%	$256.7037	$256.70	$256.70	$256.70
Purchase #6	$93.46	5.398%	$98.505	$98.51	$98.50	$98.50
Purchase #7	$230.54	11.414%	$256.8538	$256.85	$256.85	$256.90
7 purchase totals =	$1,072.33		$1,164.4946	$1,164.49	$1,164.50	$1,164.50