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	$176.59	11.252%	$196.4599	$196.46	$196.45	$196.50
Purchase #2	$122.88	13.244%	$139.1542	$139.15	$139.15	$139.20
Purchase #3	$140.32	4.836%	$147.1059	$147.11	$147.10	$147.10
Purchase #4	$196.88	11.820%	$220.1512	$220.15	$220.15	$220.20
Purchase #5	$79.71	10.838%	$88.349	$88.35	$88.35	$88.30
Purchase #6	$6.75	5.317%	$7.1089	$7.11	$7.10	$7.10
Purchase #7	$249.31	9.353%	$272.628	$272.63	$272.65	$272.60
7 purchase totals =	$972.44		$1,070.9571	$1,070.96	$1,070.95	$1,071.00