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	$128.38	9.470%	$140.5376	$140.54	$140.55	$140.50
Purchase #2	$222.72	9.253%	$243.3283	$243.33	$243.35	$243.30
Purchase #3	$6.97	4.290%	$7.269	$7.27	$7.25	$7.30
Purchase #4	$243.68	5.202%	$256.3562	$256.36	$256.35	$256.40
Purchase #5	$177.93	10.675%	$196.924	$196.92	$196.90	$196.90
Purchase #6	$87.78	9.337%	$95.976	$95.98	$96.00	$96.00
Purchase #7	$139.84	4.273%	$145.8154	$145.82	$145.80	$145.80
7 purchase totals =	$1,007.30		$1,086.2065	$1,086.22	$1,086.20	$1,086.20