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	$113.95	3.228%	$117.6283	$117.63	$117.65	$117.60
Purchase #2	$118.33	7.521%	$127.2296	$127.23	$127.25	$127.20
Purchase #3	$38.87	12.197%	$43.611	$43.61	$43.60	$43.60
Purchase #4	$189.49	10.359%	$209.1193	$209.12	$209.10	$209.10
Purchase #5	$168.55	3.334%	$174.1695	$174.17	$174.15	$174.20
Purchase #6	$175.93	9.344%	$192.3689	$192.37	$192.35	$192.40
Purchase #7	$118.49	4.578%	$123.9145	$123.91	$123.90	$123.90
7 purchase totals =	$923.61		$988.0411	$988.04	$988.00	$988.00