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	$55.47	11.333%	$61.7564	$61.76	$61.75	$61.80
Purchase #2	$190.34	5.689%	$201.1684	$201.17	$201.15	$201.20
Purchase #3	$158.38	4.713%	$165.8444	$165.84	$165.85	$165.80
Purchase #4	$196.58	6.220%	$208.8073	$208.81	$208.80	$208.80
Purchase #5	$230.68	13.833%	$262.59	$262.59	$262.60	$262.60
Purchase #6	$207.28	5.439%	$218.554	$218.55	$218.55	$218.60
Purchase #7	$68.88	5.730%	$72.8268	$72.83	$72.85	$72.80
7 purchase totals =	$1,107.61		$1,191.5473	$1,191.55	$1,191.55	$1,191.60