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	$186.73	5.683%	$197.3419	$197.34	$197.35	$197.30
Purchase #2	$118.45	7.494%	$127.3266	$127.33	$127.35	$127.30
Purchase #3	$93.54	12.600%	$105.326	$105.33	$105.35	$105.30
Purchase #4	$57.93	8.369%	$62.7782	$62.78	$62.80	$62.80
Purchase #5	$232.93	6.326%	$247.6652	$247.67	$247.65	$247.70
Purchase #6	$95.71	4.439%	$99.9586	$99.96	$99.95	$100.00
Purchase #7	$235.95	8.722%	$256.5296	$256.53	$256.55	$256.50
7 purchase totals =	$1,021.24		$1,096.9261	$1,096.94	$1,097.00	$1,096.90