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	$13.30	5.298%	$14.0046	$14.00	$14.00	$14.00
Purchase #2	$192.35	11.402%	$214.2817	$214.28	$214.30	$214.30
Purchase #3	$85.80	6.548%	$91.4182	$91.42	$91.40	$91.40
Purchase #4	$79.75	13.121%	$90.214	$90.21	$90.20	$90.20
Purchase #5	$249.37	13.443%	$282.8928	$282.89	$282.90	$282.90
Purchase #6	$119.33	7.104%	$127.8072	$127.81	$127.80	$127.80
Purchase #7	$229.98	8.787%	$250.1883	$250.19	$250.20	$250.20
7 purchase totals =	$969.88		$1,070.8068	$1,070.80	$1,070.80	$1,070.80