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	$163.81	9.642%	$179.6046	$179.60	$179.60	$179.60
Purchase #2	$134.56	6.520%	$143.3333	$143.33	$143.35	$143.30
Purchase #3	$219.54	5.619%	$231.876	$231.88	$231.90	$231.90
Purchase #4	$224.96	4.801%	$235.7603	$235.76	$235.75	$235.80
Purchase #5	$95.25	4.735%	$99.7601	$99.76	$99.75	$99.80
Purchase #6	$101.49	11.653%	$113.3166	$113.32	$113.30	$113.30
Purchase #7	$59.34	7.256%	$63.6457	$63.65	$63.65	$63.60
7 purchase totals =	$998.95		$1,067.2966	$1,067.30	$1,067.30	$1,067.30