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	$34.25	3.448%	$35.4309	$35.43	$35.45	$35.40
Purchase #2	$176.53	11.211%	$196.3208	$196.32	$196.30	$196.30
Purchase #3	$216.76	10.872%	$240.3261	$240.33	$240.35	$240.30
Purchase #4	$85.59	4.376%	$89.3354	$89.34	$89.35	$89.30
Purchase #5	$230.93	5.855%	$244.451	$244.45	$244.45	$244.50
Purchase #6	$141.69	4.322%	$147.8138	$147.81	$147.80	$147.80
Purchase #7	$134.99	12.415%	$151.749	$151.75	$151.75	$151.70
7 purchase totals =	$1,020.74		$1,105.4270	$1,105.43	$1,105.45	$1,105.30