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	$143.32	7.385%	$153.9042	$153.90	$153.90	$153.90
Purchase #2	$153.98	13.261%	$174.3993	$174.40	$174.40	$174.40
Purchase #3	$168.76	7.850%	$182.0077	$182.01	$182.00	$182.00
Purchase #4	$88.44	8.499%	$95.9565	$95.96	$95.95	$96.00
Purchase #5	$68.88	5.486%	$72.6588	$72.66	$72.65	$72.70
Purchase #6	$75.62	3.671%	$78.396	$78.40	$78.40	$78.40
Purchase #7	$130.86	5.284%	$137.7746	$137.77	$137.75	$137.80
7 purchase totals =	$829.86		$895.0971	$895.10	$895.05	$895.20