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	$177.97	10.162%	$196.0553	$196.06	$196.05	$196.10
Purchase #2	$118.66	5.585%	$125.2872	$125.29	$125.30	$125.30
Purchase #3	$196.84	4.405%	$205.5108	$205.51	$205.50	$205.50
Purchase #4	$233.74	9.767%	$256.5694	$256.57	$256.55	$256.60
Purchase #5	$91.87	5.571%	$96.9881	$96.99	$97.00	$97.00
Purchase #6	$130.61	10.635%	$144.5004	$144.50	$144.50	$144.50
Purchase #7	$71.59	9.205%	$78.1799	$78.18	$78.20	$78.20
7 purchase totals =	$1,021.28		$1,103.0911	$1,103.10	$1,103.10	$1,103.20