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	$143.28	9.524%	$156.926	$156.93	$156.95	$156.90
Purchase #2	$148.31	7.401%	$159.2864	$159.29	$159.30	$159.30
Purchase #3	$82.68	12.706%	$93.1853	$93.19	$93.20	$93.20
Purchase #4	$118.50	10.675%	$131.1499	$131.15	$131.15	$131.10
Purchase #5	$187.70	10.104%	$206.6652	$206.67	$206.65	$206.70
Purchase #6	$154.81	7.786%	$166.8635	$166.86	$166.85	$166.90
Purchase #7	$96.70	9.244%	$105.6389	$105.64	$105.65	$105.60
7 purchase totals =	$931.98		$1,019.7152	$1,019.73	$1,019.75	$1,019.70