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	$140.76	8.857%	$153.2271	$153.23	$153.25	$153.20
Purchase #2	$223.97	5.806%	$236.9737	$236.97	$236.95	$237.00
Purchase #3	$103.88	7.706%	$111.885	$111.89	$111.90	$111.90
Purchase #4	$165.67	12.471%	$186.3307	$186.33	$186.35	$186.30
Purchase #5	$52.87	12.572%	$59.5168	$59.52	$59.50	$59.50
Purchase #6	$200.76	3.170%	$207.1241	$207.12	$207.10	$207.10
Purchase #7	$206.36	12.150%	$231.4327	$231.43	$231.45	$231.40
7 purchase totals =	$1,094.27		$1,186.4901	$1,186.49	$1,186.50	$1,186.40