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	$69.26	9.823%	$76.0634	$76.06	$76.05	$76.10
Purchase #2	$98.94	12.735%	$111.54	$111.54	$111.55	$111.50
Purchase #3	$229.61	6.704%	$245.0031	$245.00	$245.00	$245.00
Purchase #4	$86.44	3.503%	$89.468	$89.47	$89.45	$89.50
Purchase #5	$218.67	5.346%	$230.3601	$230.36	$230.35	$230.40
Purchase #6	$143.50	9.612%	$157.2932	$157.29	$157.30	$157.30
Purchase #7	$143.37	9.699%	$157.2755	$157.28	$157.30	$157.30
7 purchase totals =	$989.79		$1,067.0033	$1,067.00	$1,067.00	$1,067.10