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	$224.86	4.208%	$234.3221	$234.32	$234.30	$234.30
Purchase #2	$176.35	12.352%	$198.1328	$198.13	$198.15	$198.10
Purchase #3	$102.77	5.808%	$108.7389	$108.74	$108.75	$108.70
Purchase #4	$162.27	7.217%	$173.981	$173.98	$174.00	$174.00
Purchase #5	$61.79	9.226%	$67.4907	$67.49	$67.50	$67.50
Purchase #6	$188.72	11.351%	$210.1416	$210.14	$210.15	$210.10
Purchase #7	$180.69	12.662%	$203.569	$203.57	$203.55	$203.60
7 purchase totals =	$1,097.45		$1,196.3761	$1,196.37	$1,196.40	$1,196.30