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	$98.68	12.546%	$111.0604	$111.06	$111.05	$111.10
Purchase #2	$144.47	13.618%	$164.1439	$164.14	$164.15	$164.10
Purchase #3	$64.47	10.322%	$71.1246	$71.12	$71.10	$71.10
Purchase #4	$118.40	12.167%	$132.8057	$132.81	$132.80	$132.80
Purchase #5	$146.46	8.227%	$158.5093	$158.51	$158.50	$158.50
Purchase #6	$225.96	3.428%	$233.7059	$233.71	$233.70	$233.70
Purchase #7	$198.34	12.815%	$223.7573	$223.76	$223.75	$223.80
7 purchase totals =	$996.78		$1,095.1071	$1,095.11	$1,095.05	$1,095.10