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	$146.66	3.613%	$151.9588	$151.96	$151.95	$152.00
Purchase #2	$118.28	10.182%	$130.3233	$130.32	$130.30	$130.30
Purchase #3	$166.78	3.506%	$172.6273	$172.63	$172.65	$172.60
Purchase #4	$103.34	7.559%	$111.1515	$111.15	$111.15	$111.20
Purchase #5	$89.93	8.705%	$97.7584	$97.76	$97.75	$97.80
Purchase #6	$182.63	3.572%	$189.1535	$189.15	$189.15	$189.20
Purchase #7	$78.90	10.706%	$87.347	$87.35	$87.35	$87.30
7 purchase totals =	$886.52		$940.3198	$940.32	$940.30	$940.40