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	$223.72	9.179%	$244.2553	$244.26	$244.25	$244.30
Purchase #2	$32.54	10.207%	$35.8614	$35.86	$35.85	$35.90
Purchase #3	$56.69	8.809%	$61.6838	$61.68	$61.70	$61.70
Purchase #4	$163.62	13.461%	$185.6449	$185.64	$185.65	$185.60
Purchase #5	$167.31	4.173%	$174.2918	$174.29	$174.30	$174.30
Purchase #6	$43.54	3.794%	$45.1919	$45.19	$45.20	$45.20
Purchase #7	$250.49	11.236%	$278.6351	$278.64	$278.65	$278.60
7 purchase totals =	$937.91		$1,025.5642	$1,025.56	$1,025.60	$1,025.60