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	$96.25	9.253%	$105.156	$105.16	$105.15	$105.20
Purchase #2	$32.47	8.677%	$35.2874	$35.29	$35.30	$35.30
Purchase #3	$238.89	13.530%	$271.2118	$271.21	$271.20	$271.20
Purchase #4	$196.34	7.586%	$211.2344	$211.23	$211.25	$211.20
Purchase #5	$242.64	13.278%	$274.8577	$274.86	$274.85	$274.90
Purchase #6	$144.76	4.405%	$151.1367	$151.14	$151.15	$151.10
Purchase #7	$152.56	10.626%	$168.771	$168.77	$168.75	$168.80
7 purchase totals =	$1,103.91		$1,217.6550	$1,217.66	$1,217.65	$1,217.70