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	$225.67	9.457%	$247.0116	$247.01	$247.00	$247.00
Purchase #2	$54.41	9.154%	$59.3907	$59.39	$59.40	$59.40
Purchase #3	$240.98	11.329%	$268.2806	$268.28	$268.30	$268.30
Purchase #4	$200.54	6.284%	$213.1419	$213.14	$213.15	$213.10
Purchase #5	$57.82	13.505%	$65.6286	$65.63	$65.65	$65.60
Purchase #6	$96.81	6.539%	$103.1404	$103.14	$103.15	$103.10
Purchase #7	$102.29	9.362%	$111.8664	$111.87	$111.85	$111.90
7 purchase totals =	$978.52		$1,068.4602	$1,068.46	$1,068.50	$1,068.40