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	$113.52	4.506%	$118.6352	$118.64	$118.65	$118.60
Purchase #2	$175.88	5.550%	$185.6413	$185.64	$185.65	$185.60
Purchase #3	$201.96	3.309%	$208.6429	$208.64	$208.65	$208.60
Purchase #4	$33.70	12.464%	$37.9004	$37.90	$37.90	$37.90
Purchase #5	$56.29	10.525%	$62.2145	$62.21	$62.20	$62.20
Purchase #6	$228.77	5.870%	$242.1988	$242.20	$242.20	$242.20
Purchase #7	$95.33	10.761%	$105.5885	$105.59	$105.60	$105.60
7 purchase totals =	$905.45		$960.8216	$960.82	$960.85	$960.70