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	$208.94	9.229%	$228.2231	$228.22	$228.20	$228.20
Purchase #2	$92.60	11.749%	$103.4796	$103.48	$103.50	$103.50
Purchase #3	$32.41	4.203%	$33.7722	$33.77	$33.75	$33.80
Purchase #4	$122.91	12.516%	$138.2934	$138.29	$138.30	$138.30
Purchase #5	$55.86	7.364%	$59.9735	$59.97	$59.95	$60.00
Purchase #6	$177.76	4.305%	$185.4126	$185.41	$185.40	$185.40
Purchase #7	$180.90	13.799%	$205.8624	$205.86	$205.85	$205.90
7 purchase totals =	$871.38		$955.0168	$955.00	$954.95	$955.10