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	$190.36	9.507%	$208.4575	$208.46	$208.45	$208.50
Purchase #2	$110.61	11.736%	$123.5912	$123.59	$123.60	$123.60
Purchase #3	$106.41	5.132%	$111.871	$111.87	$111.85	$111.90
Purchase #4	$12.90	4.665%	$13.5018	$13.50	$13.50	$13.50
Purchase #5	$157.58	4.776%	$165.106	$165.11	$165.10	$165.10
Purchase #6	$42.69	8.873%	$46.4779	$46.48	$46.50	$46.50
Purchase #7	$87.30	7.831%	$94.1365	$94.14	$94.15	$94.10
7 purchase totals =	$707.85		$763.1419	$763.15	$763.15	$763.20