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	$94.98	6.788%	$101.4272	$101.43	$101.45	$101.40
Purchase #2	$95.81	4.494%	$100.1157	$100.12	$100.10	$100.10
Purchase #3	$113.76	9.247%	$124.2794	$124.28	$124.30	$124.30
Purchase #4	$139.41	7.850%	$150.3537	$150.35	$150.35	$150.40
Purchase #5	$237.75	10.407%	$262.4926	$262.49	$262.50	$262.50
Purchase #6	$224.32	4.148%	$233.6248	$233.62	$233.60	$233.60
Purchase #7	$54.65	13.286%	$61.9108	$61.91	$61.90	$61.90
7 purchase totals =	$960.68		$1,034.2042	$1,034.20	$1,034.20	$1,034.20