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	$178.59	10.243%	$196.883	$196.88	$196.90	$196.90
Purchase #2	$28.44	10.455%	$31.4134	$31.41	$31.40	$31.40
Purchase #3	$24.41	5.126%	$25.6613	$25.66	$25.65	$25.70
Purchase #4	$42.31	13.846%	$48.1682	$48.17	$48.15	$48.20
Purchase #5	$203.74	6.872%	$217.741	$217.74	$217.75	$217.70
Purchase #6	$75.63	3.633%	$78.3776	$78.38	$78.40	$78.40
Purchase #7	$158.31	3.655%	$164.0962	$164.10	$164.10	$164.10
7 purchase totals =	$711.43		$762.3407	$762.34	$762.35	$762.40