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	$175.51	9.838%	$192.7767	$192.78	$192.80	$192.80
Purchase #2	$231.89	13.605%	$263.4386	$263.44	$263.45	$263.40
Purchase #3	$141.85	8.276%	$153.5895	$153.59	$153.60	$153.60
Purchase #4	$43.29	7.809%	$46.6705	$46.67	$46.65	$46.70
Purchase #5	$231.81	6.800%	$247.5731	$247.57	$247.55	$247.60
Purchase #6	$53.98	3.367%	$55.7975	$55.80	$55.80	$55.80
Purchase #7	$52.49	13.578%	$59.6171	$59.62	$59.60	$59.60
7 purchase totals =	$930.82		$1,019.4630	$1,019.47	$1,019.45	$1,019.50