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	$186.79	5.352%	$196.787	$196.79	$196.80	$196.80
Purchase #2	$30.52	5.215%	$32.1116	$32.11	$32.10	$32.10
Purchase #3	$20.28	11.485%	$22.6092	$22.61	$22.60	$22.60
Purchase #4	$36.47	6.523%	$38.8489	$38.85	$38.85	$38.80
Purchase #5	$43.63	7.391%	$46.8547	$46.85	$46.85	$46.90
Purchase #6	$139.58	11.372%	$155.453	$155.45	$155.45	$155.50
Purchase #7	$9.57	4.306%	$9.9821	$9.98	$10.00	$10.00
7 purchase totals =	$466.84		$502.6465	$502.64	$502.65	$502.70