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	$215.54	10.805%	$238.8291	$238.83	$238.85	$238.80
Purchase #2	$67.85	6.307%	$72.1293	$72.13	$72.15	$72.10
Purchase #3	$33.96	10.513%	$37.5302	$37.53	$37.55	$37.50
Purchase #4	$235.39	13.469%	$267.0947	$267.09	$267.10	$267.10
Purchase #5	$121.96	5.861%	$129.1081	$129.11	$129.10	$129.10
Purchase #6	$166.38	6.326%	$176.9052	$176.91	$176.90	$176.90
Purchase #7	$133.84	10.808%	$148.3054	$148.31	$148.30	$148.30
7 purchase totals =	$974.92		$1,069.9020	$1,069.91	$1,069.95	$1,069.80