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	$181.44	10.540%	$200.5638	$200.56	$200.55	$200.60
Purchase #2	$67.76	5.651%	$71.5891	$71.59	$71.60	$71.60
Purchase #3	$72.83	6.265%	$77.3928	$77.39	$77.40	$77.40
Purchase #4	$250.77	6.205%	$266.3303	$266.33	$266.35	$266.30
Purchase #5	$122.84	8.318%	$133.0578	$133.06	$133.05	$133.10
Purchase #6	$80.69	6.164%	$85.6637	$85.66	$85.65	$85.70
Purchase #7	$191.97	3.325%	$198.353	$198.35	$198.35	$198.40
7 purchase totals =	$968.30		$1,032.9505	$1,032.94	$1,032.95	$1,033.10