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	$148.51	9.213%	$162.1922	$162.19	$162.20	$162.20
Purchase #2	$176.73	5.477%	$186.4095	$186.41	$186.40	$186.40
Purchase #3	$174.43	4.258%	$181.8572	$181.86	$181.85	$181.90
Purchase #4	$142.29	8.133%	$153.8624	$153.86	$153.85	$153.90
Purchase #5	$234.40	12.218%	$263.039	$263.04	$263.05	$263.00
Purchase #6	$189.81	3.272%	$196.0206	$196.02	$196.00	$196.00
Purchase #7	$85.42	8.367%	$92.5671	$92.57	$92.55	$92.60
7 purchase totals =	$1,151.59		$1,235.9480	$1,235.95	$1,235.90	$1,236.00