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	$242.82	8.223%	$262.7871	$262.79	$262.80	$262.80
Purchase #2	$20.91	3.123%	$21.563	$21.56	$21.55	$21.60
Purchase #3	$106.74	13.133%	$120.7582	$120.76	$120.75	$120.80
Purchase #4	$85.42	5.186%	$89.8499	$89.85	$89.85	$89.80
Purchase #5	$199.32	10.146%	$219.543	$219.54	$219.55	$219.50
Purchase #6	$106.85	6.634%	$113.9384	$113.94	$113.95	$113.90
Purchase #7	$248.80	13.739%	$282.9826	$282.98	$283.00	$283.00
7 purchase totals =	$1,010.86		$1,111.4222	$1,111.42	$1,111.45	$1,111.40