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	$214.65	11.231%	$238.7573	$238.76	$238.75	$238.80
Purchase #2	$12.36	9.181%	$13.4948	$13.49	$13.50	$13.50
Purchase #3	$38.58	13.658%	$43.8493	$43.85	$43.85	$43.80
Purchase #4	$38.70	7.479%	$41.5944	$41.59	$41.60	$41.60
Purchase #5	$141.91	9.683%	$155.6511	$155.65	$155.65	$155.70
Purchase #6	$200.29	11.488%	$223.2993	$223.30	$223.30	$223.30
Purchase #7	$57.89	7.802%	$62.4066	$62.41	$62.40	$62.40
7 purchase totals =	$704.38		$779.0528	$779.05	$779.05	$779.10