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	$59.36	3.195%	$61.2566	$61.26	$61.25	$61.30
Purchase #2	$152.45	3.755%	$158.1745	$158.17	$158.15	$158.20
Purchase #3	$114.86	5.753%	$121.4679	$121.47	$121.45	$121.50
Purchase #4	$174.79	5.665%	$184.6919	$184.69	$184.70	$184.70
Purchase #5	$166.80	4.598%	$174.4695	$174.47	$174.45	$174.50
Purchase #6	$217.42	13.507%	$246.7869	$246.79	$246.80	$246.80
Purchase #7	$62.57	13.570%	$71.0607	$71.06	$71.05	$71.10
7 purchase totals =	$948.25		$1,017.9080	$1,017.91	$1,017.85	$1,018.10