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	$81.68	4.257%	$85.1571	$85.16	$85.15	$85.20
Purchase #2	$110.68	11.256%	$123.1381	$123.14	$123.15	$123.10
Purchase #3	$223.97	5.295%	$235.8292	$235.83	$235.85	$235.80
Purchase #4	$32.57	7.372%	$34.9711	$34.97	$34.95	$35.00
Purchase #5	$70.36	3.438%	$72.779	$72.78	$72.80	$72.80
Purchase #6	$89.39	7.194%	$95.8207	$95.82	$95.80	$95.80
Purchase #7	$82.48	4.346%	$86.0646	$86.06	$86.05	$86.10
7 purchase totals =	$691.13		$733.7598	$733.76	$733.75	$733.80