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	$227.31	6.727%	$242.6011	$242.60	$242.60	$242.60
Purchase #2	$245.88	6.651%	$262.2335	$262.23	$262.25	$262.20
Purchase #3	$94.98	7.530%	$102.132	$102.13	$102.15	$102.10
Purchase #4	$93.31	10.347%	$102.9648	$102.96	$102.95	$103.00
Purchase #5	$86.55	9.325%	$94.6208	$94.62	$94.60	$94.60
Purchase #6	$157.31	8.700%	$170.996	$171.00	$171.00	$171.00
Purchase #7	$56.58	4.361%	$59.0475	$59.05	$59.05	$59.00
7 purchase totals =	$961.92		$1,034.5957	$1,034.59	$1,034.60	$1,034.50