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	$214.87	10.701%	$237.8632	$237.86	$237.85	$237.90
Purchase #2	$69.65	4.490%	$72.7773	$72.78	$72.80	$72.80
Purchase #3	$240.71	11.661%	$268.7792	$268.78	$268.80	$268.80
Purchase #4	$169.92	9.163%	$185.4898	$185.49	$185.50	$185.50
Purchase #5	$187.91	4.610%	$196.5727	$196.57	$196.55	$196.60
Purchase #6	$217.27	6.756%	$231.9488	$231.95	$231.95	$231.90
Purchase #7	$236.46	5.254%	$248.8836	$248.88	$248.90	$248.90
7 purchase totals =	$1,336.79		$1,442.3146	$1,442.31	$1,442.35	$1,442.40