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	$63.81	13.797%	$72.6139	$72.61	$72.60	$72.60
Purchase #2	$43.64	5.611%	$46.0886	$46.09	$46.10	$46.10
Purchase #3	$144.59	6.671%	$154.2356	$154.24	$154.25	$154.20
Purchase #4	$110.44	12.537%	$124.2859	$124.29	$124.30	$124.30
Purchase #5	$165.81	3.618%	$171.809	$171.81	$171.80	$171.80
Purchase #6	$93.28	9.479%	$102.122	$102.12	$102.10	$102.10
Purchase #7	$104.33	6.783%	$111.4067	$111.41	$111.40	$111.40
7 purchase totals =	$725.90		$782.5617	$782.57	$782.55	$782.50