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	$43.37	4.533%	$45.336	$45.34	$45.35	$45.30
Purchase #2	$65.58	8.161%	$70.932	$70.93	$70.95	$70.90
Purchase #3	$165.38	3.669%	$171.4478	$171.45	$171.45	$171.40
Purchase #4	$93.98	5.786%	$99.4177	$99.42	$99.40	$99.40
Purchase #5	$40.56	4.294%	$42.3016	$42.30	$42.30	$42.30
Purchase #6	$206.44	4.126%	$214.9577	$214.96	$214.95	$215.00
Purchase #7	$39.64	11.635%	$44.2521	$44.25	$44.25	$44.30
7 purchase totals =	$654.95		$688.6449	$688.65	$688.65	$688.60