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	$172.75	13.611%	$196.263	$196.26	$196.25	$196.30
Purchase #2	$173.98	9.712%	$190.8769	$190.88	$190.90	$190.90
Purchase #3	$222.83	5.208%	$234.435	$234.44	$234.45	$234.40
Purchase #4	$155.76	3.646%	$161.439	$161.44	$161.45	$161.40
Purchase #5	$181.59	8.343%	$196.7401	$196.74	$196.75	$196.70
Purchase #6	$148.55	4.642%	$155.4457	$155.45	$155.45	$155.40
Purchase #7	$210.71	5.339%	$221.9598	$221.96	$221.95	$222.00
7 purchase totals =	$1,266.17		$1,357.1595	$1,357.17	$1,357.20	$1,357.10