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	$34.65	3.191%	$35.7557	$35.76	$35.75	$35.80
Purchase #2	$56.33	5.497%	$59.4265	$59.43	$59.45	$59.40
Purchase #3	$198.43	3.190%	$204.7599	$204.76	$204.75	$204.80
Purchase #4	$84.94	6.712%	$90.6412	$90.64	$90.65	$90.60
Purchase #5	$209.28	10.314%	$230.8651	$230.87	$230.85	$230.90
Purchase #6	$141.65	6.738%	$151.1944	$151.19	$151.20	$151.20
Purchase #7	$240.38	12.589%	$270.6414	$270.64	$270.65	$270.60
7 purchase totals =	$965.66		$1,043.2842	$1,043.29	$1,043.30	$1,043.30