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	$76.87	11.415%	$85.6447	$85.64	$85.65	$85.60
Purchase #2	$119.42	6.511%	$127.1954	$127.20	$127.20	$127.20
Purchase #3	$68.27	4.547%	$71.3742	$71.37	$71.35	$71.40
Purchase #4	$175.71	3.454%	$181.779	$181.78	$181.80	$181.80
Purchase #5	$73.40	4.810%	$76.9305	$76.93	$76.95	$76.90
Purchase #6	$121.64	7.132%	$130.3154	$130.32	$130.30	$130.30
Purchase #7	$148.83	7.719%	$160.3182	$160.32	$160.30	$160.30
7 purchase totals =	$784.14		$833.5574	$833.56	$833.55	$833.50