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	$162.58	5.572%	$171.639	$171.64	$171.65	$171.60
Purchase #2	$83.30	8.295%	$90.2097	$90.21	$90.20	$90.20
Purchase #3	$93.68	8.619%	$101.7543	$101.75	$101.75	$101.80
Purchase #4	$23.53	5.761%	$24.8856	$24.89	$24.90	$24.90
Purchase #5	$209.89	12.255%	$235.612	$235.61	$235.60	$235.60
Purchase #6	$54.76	12.365%	$61.5311	$61.53	$61.55	$61.50
Purchase #7	$66.34	7.421%	$71.2631	$71.26	$71.25	$71.30
7 purchase totals =	$694.08		$756.8948	$756.89	$756.90	$756.90