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	$135.36	7.380%	$145.3496	$145.35	$145.35	$145.30
Purchase #2	$66.97	6.488%	$71.315	$71.32	$71.30	$71.30
Purchase #3	$171.72	10.741%	$190.1644	$190.16	$190.15	$190.20
Purchase #4	$216.97	5.302%	$228.4737	$228.47	$228.45	$228.50
Purchase #5	$170.41	12.586%	$191.8578	$191.86	$191.85	$191.90
Purchase #6	$154.56	3.307%	$159.6713	$159.67	$159.65	$159.70
Purchase #7	$74.95	7.417%	$80.509	$80.51	$80.50	$80.50
7 purchase totals =	$990.94		$1,067.3408	$1,067.34	$1,067.25	$1,067.40