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	$115.32	10.347%	$127.2522	$127.25	$127.25	$127.30
Purchase #2	$146.66	3.303%	$151.5042	$151.50	$151.50	$151.50
Purchase #3	$250.54	9.333%	$273.9229	$273.92	$273.90	$273.90
Purchase #4	$114.46	10.543%	$126.5275	$126.53	$126.55	$126.50
Purchase #5	$64.56	3.610%	$66.8906	$66.89	$66.90	$66.90
Purchase #6	$114.79	3.729%	$119.0705	$119.07	$119.05	$119.10
Purchase #7	$133.55	8.354%	$144.7068	$144.71	$144.70	$144.70
7 purchase totals =	$939.88		$1,009.8747	$1,009.87	$1,009.85	$1,009.90