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	$177.63	10.790%	$196.7963	$196.80	$196.80	$196.80
Purchase #2	$47.82	3.155%	$49.3287	$49.33	$49.35	$49.30
Purchase #3	$165.73	4.370%	$172.9724	$172.97	$172.95	$173.00
Purchase #4	$46.25	13.135%	$52.3249	$52.32	$52.30	$52.30
Purchase #5	$65.74	8.795%	$71.5218	$71.52	$71.50	$71.50
Purchase #6	$30.57	6.210%	$32.4684	$32.47	$32.45	$32.50
Purchase #7	$165.65	12.456%	$186.2834	$186.28	$186.30	$186.30
7 purchase totals =	$699.39		$761.6959	$761.69	$761.65	$761.70